# Arcane Arsenal . ### A Modular Firearms System for Fifth Edition --- . ## Dungeons & Dragons Community Content . --- Arcane Arsenal is published under the Dungeon Masters Guild Community Content Agreement. DUNGEONS & DRAGONS, D&D, Wizards of the Coast, and all related logos and trademarks are property of Wizards of the Coast LLC. --- © 2025 Sordia Vignti. All original content in this work is published under the Dungeon Masters Guild Community Content Agreement. --- . ## Credits **Design & Writing:** AbnormalOrchid **System Development:** Arcane Arsenal Playtest Group **Editing & Layout:** Sordia Vignti **Cover Art:** Sordia Vignti --- . ## Introduction . ### The Philosophy of Modular Weapons Magic weapons in many campaigns follow a predictable path. A character acquires A +1 weapon, later replaces it with a +2 weapon, and eventually discards it for something stronger. Progression becomes linear and transactional. --- Arcane Arsenal replaces that model. --- This system treats firearms not as disposable upgrades, but as evolving instruments of mastery. A modular firearm is refined, re-engineered, and customised over time. Its identity is defined by deliberate mechanical trade-offs and tactical specialisation. --- Rather than stacking passive bonuses, Arcane Arsenal emphasises meaningful choices. A limited number of modification slots forces prioritisation. Do you extend range or enhance battlefield control? Do you increase burst potential or sustain? Each modification changes how the weapon behaves — not merely how much damage it deals. --- This system is built around horizontal progression rather than vertical escalation. --- . ## Design Intent Arcane Arsenal is guided by five core principles: 1. **Tactical Depth Over Raw Scaling.** Power comes from situational advantages, not flat numerical increases. Strong effects require trade-offs. Synergy must be earned. 2. **Martial Spotlight Protection.** Modular firearms enhance martial characters without eclipsing spellcasters or violating action economy expectations. 3. **Controlled Power Ceiling.** Strict slot limits prevent stacking abuse. Even Legendary-tier weapons obey structural constraints. 4. **Identity Through Construction.** Two characters with the same base platform can create entirely different weapons through modification choices. 5. **Dungeon Master Stability.** Mandatory balancing rules prevent unintended interactions and preserve encounter integrity. --- . ## What This System Is Arcane Arsenal is not a simulation of modern firearms. It does not model gunpowder physics or real-world ballistics. --- These weapons are arcane constructs, a fusion of rune-etched engineering, elemental cores, artificer craftsmanship, and magical refinement. --- They can fit seamlessly into high magitech societies, planar campaigns, arcane-industrial settings, or rare experimental guild traditions in traditional fantasy worlds. --- . ## What It Is Not This system is not intended to replace traditional magic weapons. It provides an alternative progression path for campaigns where modular arcane weaponry fits the tone. --- \page ## Using This System in Your Campaign Arcane Arsenal can be introduced in several ways: - As secret artificer technology guarded by a powerful guild - As relics of a fallen arcane empire - As planar constructs powered by elemental fragments - As experimental military prototypes - As signature weapons forged for specific heroes The Dungeon Master determines availability. Blueprint access, rarity restrictions, and material scarcity can all be used to maintain tone and balance. In low-magic campaigns, modular firearms may be legendary artefacts. In high-magic settings, they may represent elite martial craftsmanship. --- . ## The Core Concept A modular firearm consists of: 1. A Base Gun 2. A number of Modification Slots Each installed modification occupies one slot. A weapon can never exceed its slot capacity. No amount of gold, crafting expertise, or magical enhancement can bypass this structural limitation. This constraint is the backbone of the system. It ensures tactical trade-offs, controlled scaling, clear build identity, and mechanical clarity. Characters do not accumulate infinite upgrades. They refine within limits. --- . ## Structure of This Book Arcane Arsenal is divided into the following sections: - Core System Rules - Base Gun Archetypes - Modular Components - Crafting & Blueprint System - Feats & Character Options - Example Builds - Legendary Signature Weapons - Advanced Optional Rules - Dungeon Master Integration Guide - Appendices & Quick Reference Tables Each chapter builds upon the previous one. Groups may adopt as much or as little complexity as suits their campaign. --- \page # Chapter 1: Core System Rules . ## What Is a Modular Firearm? A modular firearm is a magical ranged weapon built around interchangeable components. Rather than possessing fixed enchantments, it gains its abilities from installed modifications. These modifications represent physical and arcane augmentations such as elemental coils, reinforced receivers, rune-etched chambers, void-powered cores, tactical lenses, and structural stabilisers. The base weapon determines the foundational profile, damage dice, range, and handling, while installed modifications alter behaviour. --- . ## Base Gun Rarity & Slot Capacity Before installing modifications, a character must possess a base firearm. Each base gun has a rarity that determines slot capacity. | Rarity | Mod Slots | Typical Cost (gp) | |----------|----------:|------------------:| | Common | 1 | 200 | | Uncommon | 2 | 750 | | Rare | 3 | 1,500 | | Very Rare| 4 | 4,000 | | Legendary| 5+ | 10,000+ | Gold cost reflects craftsmanship, not raw power. Balance is governed primarily by slot limits rather than price. --- . ## Installing and Removing Mods Installing or removing a modification requires: - 1 hour of uninterrupted work - Appropriate tools (typically Tinker’s Tools, Smith’s Tools, or equivalent at DM discretion) - Access to the mod component Mods cannot be installed or removed during combat. The DM may require an Intelligence (Tool) check for rare, delicate, or experimental components. A removed modification remains intact unless destroyed by special conditions. --- . --- . ## Mandatory Balance Rules These rules are mandatory and exist to protect action economy and prevent stacking abuse. ### 1) Slot Limit Each mod occupies one slot. A weapon cannot exceed its slot capacity. Duplicate mods cannot be installed. ### 2) Attack Economy Limit No more than one mod may grant additional attacks. A weapon may never exceed standard action economy limits. ### 3) Critical Effect Limit Only one mod-triggered critical effect may activate per turn. If multiple effects qualify, the wielder chooses which applies. ### 4) Control Effect Lockout A creature can suffer only one movement- or reaction-denying mod effect per round from a single weapon. This includes: - Speed reduction - Restrained effects - Reaction denial - Forced immobilisation If multiple effects would apply, the wielder chooses which takes effect. ### 5) Area Effect Limit Only one cone, line, or area-of-effect mod may be installed on a weapon at a time. ### 6) Repeater Restriction If a weapon fires more than once per action due to a modification: - The additional hit cannot trigger rune or magazine effects - The additional hit cannot benefit from Sneak Attack (or similar “once per turn” rider effects) - The additional hit deals base weapon damage only, unless a feature explicitly says otherwise ### 7) Weapon’s Base Damage Dice If multiple modifications would alter a weapon’s base damage dice, only one such modification can apply at a time. The wielder chooses which modification determines the base damage. --- \page # Chapter 2: Base Gun Archetypes A base gun is the structural foundation of a modular firearm. It determines the weapon’s core damage profile, range, handling characteristics, and mod capacity. Modifications shape behaviour, but the base platform defines identity. Each base gun includes core statistics, base traits, slot range by rarity, and intended battlefield role. The Dungeon Master determines availability and rarity. --- . --- . ## Arcanepistol Light, compact, and versatile. **Weapon Type:** Martial Ranged Weapon **Base Damage:** 1d10 piercing **Range:** 60/180 ft **Properties:** Light **Slots by Rarity:** 1–3 **Platform Traits** - Built for mobility and close-quarters precision - Easier to conceal than larger platforms - Ideal for skirmishers, rogues, and artificer-style characters The Arcanepistol thrives in dynamic combat. Its modest reach limits long-distance dominance without modification, but its handling supports aggressive repositioning and fast tempo. --- . --- . --- . ## Runeblade Carbine Balanced, adaptable, and reliable. **Weapon Type:** Martial Ranged Weapon **Base Damage:** 1d12 piercing **Range:** 80/240 ft **Properties:** Two-Handed **Slots by Rarity:** 2–4 **Platform Traits** - General-purpose modular rifle - Designed for mid-range engagements - Common military pattern in organised forces The Runeblade Carbine is the baseline rifle platform: flexible, dependable, and highly compatible with elemental conversions, stabilisation upgrades, and precision optics. --- . --- . --- . ## Stormreaver Rifle Long-range dominance platform. **Weapon Type:** Martial Ranged Weapon **Base Damage:** 2d6 piercing **Range:** 120/360 ft **Properties:** Two-Handed, Heavy **Slots by Rarity:** 2–5 **Platform Traits** - Built to control sightlines - Less practical in confined spaces - Ideal for snipers and controllers The Stormreaver Rifle excels when it can dictate distance. It pairs well with scope and barrel modifications that push precision, reach, and elemental pressure. --- . ## Scatterblaster Devastating at close range. **Weapon Type:** Martial Ranged Weapon **Base Damage:** 2d8 piercing **Range:** 30/90 ft **Properties:** Two-Handed **Slots by Rarity:** 1–4 **Platform Traits** - High burst potential at short range - Poor long-range performance - Suited to shock assault and corridor fighting The Scatterblaster rewards positioning and nerve. It synergises strongly with cone muzzles and short-range control, but its reach ensures it cannot dominate every encounter type. --- . ## Voidline Sniper Precision instrument of elimination. **Weapon Type:** Martial Ranged Weapon **Base Damage:** 2d10 piercing **Range:** 150/500 ft **Properties:** Two-Handed, Heavy **Slots by Rarity:** 2–5 **Platform Traits** - Extreme-range lethality - Weak in close quarters - Strong synergy with stationary and aiming bonuses The Voidline Sniper is built for deliberate play: sightlines, patience, and overwatch. In open terrain, siege scenarios, or large battle maps, it becomes a defining platform. --- \page ## Magebreaker Cannon Anti-magic siege platform. **Weapon Type:** Martial Ranged Weapon **Base Damage:** 2d12 piercing **Range:** 100/300 ft **Properties:** Two-Handed, Heavy **Slots by Rarity:** 3–5 **Platform Traits** - High-impact engagements - Often restricted to elite operators - Designed to pair with disruption and nullification mods Because of its damage profile and intended role, the Magebreaker Cannon is best handled as a rare battlefield tool rather than everyday gear. --- . --- . ## Relic-Class Handcannon Signature weapon platform. **Weapon Type:** Martial Ranged Weapon **Base Damage:** 1d12 piercing (one-handed), 2d6 piercing (two-handed) **Range:** 80/240 ft **Properties:** Versatile **Slots by Rarity:** 3–5 **Platform Traits** - Built as a hero’s signature weapon - Flexible across combat styles - Often bound by story, oath, or legacy Relic-Class Handcannons are seldom mass-produced. They represent bespoke craftsmanship and are ideal candidates for personalised builds and long-term character identity. --- . --- . ## Base Platform Balance Notes These principles guide platform balance: - Higher damage typically comes with reduced mobility or constrained engagement range - Heavy platforms reward positioning and punish poor movement - Short-range platforms provide burst but increase exposure - No platform is universally superior; identity emerges through mods --- . ## Dungeon Masters may: - Restrict platforms by region or faction - Tie advanced platforms to quests and reputation - Require attunement at Very Rare or Legendary tiers --- \page # Chapter 3: Modular Components Modular Components are the interchangeable elements that define how a firearm behaves. Each modification represents a physical or magical augmentation installed into a base weapon. Every mod: - Occupies one slot - Cannot be duplicated on the same weapon - Cannot exceed the weapon’s slot capacity - Is subject to the Mandatory Balance Rules in Chapter 1 Unless otherwise specified, a mod effect can trigger only once per turn. --- --- . ## Saving Throw DC Unless otherwise specified: --- **Mod Save DC = 8 + Proficiency Bonus + DEX modifier** --- . --- If a character uses a different ability score for firearm attacks (such as Intelligence through a class feature), they may use that modifier instead. --- . ## Mod Tiers . --- | Tier | Access | |-----------|----------------------------------------------------------| | Standard | Available in major arcane centres | | Advanced | Requires specialist crafting or faction access | | Prototype | Rare schematics, Rewards, or experimental designs | --- . --- Gold cost reflects craftsmanship and rarity, not raw combat strength. --- --- . \page ## Barrel & Muzzle Mods --- Barrel and muzzle modifications alter range, damage type, and projectile behaviour. --- Only one area-of-effect barrel mod may be installed on a weapon at a time. --- . --- . ### Longbite Barrel (Standard Tier) Your weapon’s normal and long ranges each increase by 100 feet. You gain a +1 bonus to attack rolls made at long range. You suffer a −2 penalty to attack rolls against targets within 20 feet. --- . --- . ### Stormcoil Barrel (Advanced Tier) Your weapon deals lightning damage instead of piercing damage. When you score a critical hit, lightning arcs to one creature of your choice within 10 feet of the original target. The secondary creature must make a Dexterity saving throw. On a failure, it takes lightning damage equal to your proficiency bonus. This arc damage may occur once per turn. --- --- . ### Hexfire Coil Barrel (Advanced Tier) Your weapon deals fire damage instead of piercing damage. When you score a critical hit, the target ignites. At the start of each of its turns, it takes 1d6 fire damage. The creature may repeat a Dexterity saving throw at the end of each of its turns, ending the effect on a success. Only one creature may be ignited by this mod at a time. --- --- . ### Scattershock Muzzle (Standard Tier — Area Effect) When you take the Attack action, you may replace one attack with a 15-foot cone blast. Creatures in the area must make a Dexterity saving throw. - On a failure, a creature takes your weapon’s damage. - On a success, it takes half as much damage. This counts as your one allowed area-of-effect mod. --- . --- . --- . ### Astral Piercer Barrel (Prototype Tier) Your attacks ignore half and three-quarters cover. When you score a critical hit, the target must succeed on a Charisma saving throw or be banished to a harmless demiplane until the end of its next turn. This banishment may occur once per turn. --- ### Blunderbore Muzzle (Standard Tier — Area Effect) When you take the Attack action, you may replace one attack with a 15-foot cone blast. Creatures in the cone must make a Dexterity saving throw. - On a failure, they take half your weapon’s normal damage and are pushed 5 feet away from you. - On a success, they take no damage. This counts as your one allowed area-of-effect mod. --- . ### Frostbite Barrel (Advanced Tier) Your weapon deals cold damage instead of piercing damage. On a hit, the target’s speed is reduced by 10 feet until the end of its next turn. This reduction cannot stack with other speed reductions from this weapon. --- . ### Silencer Coil (Standard Tier) When you hit a creature, the attack does not reveal your position through sound. This does not prevent visual detection or magical detection. --- . ### Phasewave Muzzle (Advanced Tier) When you hit a creature, it must succeed on a Strength saving throw or be pushed 10 feet directly away from you. This forced movement counts toward the Control Effect Lockout rule. --- \page ## Frame & Receiver Mods Frame and receiver modifications alter how the weapon fires. These define cadence, damage structure, and attack behaviour. --- Only one mod may grant additional attacks. --- . --- . ### Repeater Frame (Advanced Tier) When you take the Attack action with this weapon, you may make one additional attack as part of that action. --- The additional attack: - Cannot trigger rune or magazine effects - Cannot benefit from Sneak Attack or similar features - Deals base weapon damage only You may not install another mod that grants additional attacks. --- . ### Mortis Core Receiver (Prototype Tier) Your weapon deals necrotic damage instead of piercing damage. --- When you reduce a creature to 0 hit points with this weapon, you regain hit points equal to your proficiency bonus + your Dexterity modifier. This healing may occur once per turn. --- . --- . ### Stormrider Frame (Advanced Tier — Area Effect) As an action, you may fire a 30-foot-long, 5-foot-wide line of lightning. Creatures in the line must make a Dexterity saving throw. - On a failure, a creature takes your weapon’s damage. - On a success, it takes half as much damage. Once per short rest. This counts as your one allowed area-of-effect mod. --- . --- . ### Heavybolter Assembly (Standard Tier) Your weapon’s base damage becomes 2d10. --- If you do not move during your turn, you have advantage on attack rolls with this weapon until the end of your turn. --- Your speed is reduced by 10 feet while wielding this weapon. --- . --- . ### Sniper Frame (Standard Tier) Your weapon’s base damage becomes 2d12. --- When you hit a target at long range, you deal an additional 1d10 damage. This bonus damage may occur once per turn. --- . ### Overclock Frame (Advanced Tier) Increase your weapon’s damage dice by one step (for example, 1d10 becomes 1d12; 2d6 becomes 2d8). --- If you roll a natural 1 on an attack roll with this weapon, it jams. Clearing the jam requires an action. --- . --- . ### Sentinel Frame (Advanced Tier) You may make opportunity attacks with this weapon. These attacks do not suffer disadvantage for being made in melee. --- . --- . ### Arc Capacitor Core (Standard Tier) The first time you hit a creature after reloading this weapon, you deal an additional 1d10 damage. This bonus damage may occur once per reload cycle. --- . \page ## Stock & Grip Mods Stock and grip modifications improve control, posture, and handling. --- . ### Gyroscopic Stabiliser Stock (Standard Tier) Once per attack, you may reroll one weapon damage die. You must use the new result. --- While prone, you have advantage on attack rolls with this weapon. --- . --- . ### Witchwood Handgrip (Advanced Tier) When you hit a creature, you may mark it. While marked, the creature takes an additional 1d6 damage from your weapon attacks. --- The mark lasts for 1 minute or until you mark another creature. This mark does not require concentration. Only one creature may be marked at a time. --- . --- . ### Clockwork Folding Stock (Standard Tier) You have advantage on Dexterity (Sleight of Hand) checks made to conceal this weapon. --- When you hit a surprised creature, you deal an additional 1d6 damage. This bonus damage may occur once per combat. --- . --- . ### Tinker’s Counterweight Grip (Standard Tier) You do not suffer disadvantage on ranged attack rolls made while within 5 feet of a hostile creature. --- You have advantage on ability checks made to resist being disarmed. --- \page ## Magazine & Power Core Mods Magazine and core modifications alter sustained effects, elemental infusion, and battlefield pressure. --- Unless otherwise stated, a magazine effect may trigger only once per turn. --- . --- . --- . ### Alkahest Core (Advanced Tier) Your weapon deals acid damage instead of piercing damage. --- When you hit a creature, its Armour Class is reduced by 1 until the start of your next turn. A creature’s AC cannot be reduced by more than 3 from this mod. --- . --- . ### Elemental Glyph Chamber (Advanced Tier) When you hit a creature, roll a d4: --- 1 — **Fire:** Target takes 1d6 fire damage. 2 — **Cold:** Target’s speed is reduced by 10 feet until end of its next turn. 3 — **Lightning:** Target cannot take reactions until start of its next turn. 4 — **Thunder:** Target is pushed 5 feet away from you. --- . --- Only one result may apply per turn. --- Effects that deny reactions or reduce speed count toward Control Lockout. --- . --- . ### Void Echo Feeder (Prototype Tier) When you make an attack roll with this weapon, you may treat the roll as if you had advantage. If you already have advantage, you instead gain a +2 bonus to the roll. --- Uses equal to your proficiency bonus per long rest. --- . --- . ### Hellsteel Drum (Standard Tier) Your weapon deals fire damage instead of piercing damage. --- You ignore resistance to fire damage. --- If you roll a natural 1 on an attack roll, you take 1d8 fire damage. --- . --- . --- . --- . ### Shattercharge Feed (Prototype Tier) When you score a critical hit for the first time on your turn, the target must make a Constitution saving throw. - On a failure, it is stunned until the end of your next turn. - On a success, it takes additional damage equal to your proficiency bonus. Once per long rest. --- . --- . ### Bloodstone Magazine (Advanced Tier) Once per turn when you deal damage with this weapon, you gain temporary hit points equal to your proficiency bonus. These temporary hit points do not stack with themselves. --- . --- . ### Nullfield Core (Prototype Tier) When you hit a creature, you may force it to make a Constitution saving throw. On a failure, you suppress one magical effect currently affecting it (your choice) until the end of its next turn. --- This cannot suppress artefacts, effects above 5th level, or class features. --- Once per short rest. --- . --- . \page ## Rune Mods Rune modifications represent powerful arcane inscriptions. --- --- . ### Runestone of Echoes (Advanced Tier) When you miss with an attack, you may deal damage equal to your proficiency bonus to a different creature within 10 feet of the original target. --- Once per turn. --- --- . --- . ### Sigil of Time Dilation (Prototype Tier) Before initiative is rolled, you may make one attack with this weapon. This attack: - Cannot benefit from Sneak Attack - Cannot trigger additional mod effects - Does not grant advantage --- Once per long rest. --- --- . --- . ### Phantom Round Circuitry (Advanced Tier) Your shots can pass through up to 1 foot of nonmagical material. --- You cannot score critical hits while this mod is installed. --- --- . --- . ### Cursebrand Etching (Prototype Tier) When you hit a creature, you may brand it. For 1 minute, the creature cannot take opportunity attacks. --- Once per long rest. --- --- . --- . ### Rune of Returning (Standard Tier) As a bonus action, you may teleport this weapon into your hand if it is within 60 feet and not held by another creature. --- Once per short rest. --- --- . --- . --- . \page ## Utility Mods Utility modifications provide tactical flexibility. --- --- . --- . ### Bayonet Spike (Standard Tier) As a bonus action, you may make a melee weapon attack with this weapon (1d6 piercing damage). --- --- . --- . ### Grapnel Launcher (Advanced Tier) As an action, you fire a grappling line to a solid surface within 60 feet. You may pull yourself to that location or secure a rope. --- Three uses per long rest. --- --- . --- . ### Quick-Release Sling (Standard Tier) You may draw or stow this weapon without using your object interaction. --- . --- . ### Smoke Discharge Valve (Advanced Tier) As an action, create a 10-foot-radius sphere of heavily obscured smoke centred on a point within 30 feet. The smoke lasts until the start of your next turn. --- Once per long rest. --- --- . --- . ### Flashburst Chamber (Standard Tier) As an action, creatures within 15 feet must succeed on a Constitution saving throw or be blinded until the end of their next turn. --- Once per short rest. --- --- . --- . ### Auto-Brace Bipod (Standard Tier) If you do not move during your turn, you gain +2 AC against ranged attacks until the start of your next turn. --- --- . --- . --- . ### Shock Net Launcher (Advanced Tier) As an action, target a creature within 30 feet. It must succeed on a Dexterity saving throw or be restrained until the end of its next turn. --- Once per short rest. Counts toward Control Lockout. --- --- . --- . ### Flare Beacon (Standard Tier) As an action, launch a flare to a point within 60 feet. Creatures in a 20-foot radius are brightly illuminated, and invisible creatures in the area become visible until the start of your next turn. --- Once per long rest. --- \page ## Scope Mods Scope modifications enhance awareness, targeting, and positional advantage. Scope mods do not change damage type or dice; they improve information and accuracy through tactical optics, voidglass lenses, and rune-aligned prisms. --- Only one Scope mod can be installed on a weapon at a time. --- --- . --- . ### Tactical Lens Array (Standard Tier) While this mod is installed, you gain the following benefits: - Your passive Wisdom (Perception) increases by 5. - You have advantage on Wisdom (Perception) checks made to spot hidden creatures while you are holding the weapon. - You add your proficiency bonus to initiative rolls while you are holding the weapon. --- --- . --- . ### Voidglass Scope (Prototype Tier) While holding the weapon, you can see invisible creatures within 60 feet of you, provided you have line of sight to them. You can also see into the Ethereal Plane within 60 feet of you, as if it were normal vision. --- This does not allow you to see through solid objects. --- . --- . ### Snipeglass Prism (Advanced Tier) If you do not move on your turn, you gain advantage on the first attack roll you make with this weapon before the end of that turn. --- \page # Chapter 4: Crafting & Blueprint System Modular firearms are not merely purchased, they are engineered. Basic components may be available in major arcane centres, but Advanced and Prototype modifications are typically gated behind schematics, rare materials, specialist labour, and downtime. --- This chapter provides a crafting structure designed to integrate with downtime, quest rewards and treasure progression without replacing your campaign’s existing economy. --- . ## Crafting Overview To craft a modification, a character must possess all of the following: 1. The appropriate Blueprint (Schematic) 2. The required materials (or a gold substitute) 3. A relevant tool proficiency 4. The required downtime --- Crafting is performed during downtime and cannot be completed during combat, short rests, or while travelling at a forced pace. --- . ## Blueprints & Schematics A blueprint represents the specialised knowledge required to build a modification safely and reliably. Blueprints may be: - Purchased from master artificers - Found in lost workshops - Recovered from ruined arcane laboratories - Awarded as quest rewards - Reverse-engineered (DM discretion) --- A character cannot normally craft a mod without its blueprint. The DM may allow experimental crafting (see below), but it carries risk. --- Blueprints are valuable loot. Many factions treat them like military secrets. --- . ## Required Tool Proficiencies Crafting a modular component typically requires proficiency with one of the following (DM discretion): - Tinker’s Tools - Smith’s Tools - Artificer’s Tools - Arcana Profiency for certain rune-etched or planar components --- ## Crafting Time Crafting time is determined by tier: | Mod Tier | Downtime Required | |----------|-------------------| | Standard | 2 days | | Advanced | 5 days | | Prototype| 10 days | --- Downtime assumes approximately 8 hours of work per day. --- **Skilled Efficiency.** At the start of crafting, you may attempt an Intelligence (tools) check (DC 15). On a success, you reduce the crafting time by 1 day (minimum 1). On a failure, crafting time is unchanged. --- . ## Crafting Cost Crafting cost is half the suggested gold value of the mod. This represents materials, subcomponents, calibration crystals, and workshop consumables. --- The DM may allow rare materials to replace part of this cost. (DM discretion) --- . ## Rare Materials (Optional Hooks) Advanced and Prototype mods often require materials that cannot be purchased at market value or that are controlled by factions. Rare materials may replace up to 25% of a mod’s crafting cost (DM discretion). Some Prototype mods may require a specific material. --- **Elemental Heartstone.** A condensed shard of elemental energy harvested from powerful elementals. *Common Uses:* Stormcoil Barrel, Frostbite Barrel, Elemental Glyph Chamber --- **Dragonbone Frame Core.** A carved and reinforced segment of ancient dragon bone stabilised through enchantment. *Common Uses:* Sniper Frame, Heavybolter Assembly, Legendary weapon crafting --- **Void Crystal.** Crystallised planar energy drawn from the Astral Sea, Shadowfell, or the space between planes. *Common Uses:* Astral Piercer Barrel, Voidglass Scope, Void Echo Feeder, Nullfield Core --- **Infernal Alloy.** Heat-resistant metal forged under extreme pressure and supernatural heat. *Common Uses:* Hellsteel Drum, Overclock Frame --- **Celestial Filament.** Radiant-threaded arcane wiring woven from divine energy. *Common Uses:* Sigil of Time Dilation, rune modifications --- \page ## Experimental Crafting A character may attempt to craft a mod without possessing its blueprint. This is risky, slower, and less predictable. --- When attempting experimental crafting: - Crafting time increases by 50% (round up). - At completion, you must make an Intelligence (tools) check using the DC below. | Mod Tier | DC | |----------|---:| | Standard | 14 | | Advanced | 17 | | Prototype| 20 | --- On a failure, roll on the Experimental Instability Table. --- . ### Experimental Instability Table (1d6) 1. **Component instability:** The mod functions, but its critical-hit riders (if any) never trigger. --- 2. **Overload:** The first time you use the mod in combat, you take 1d6 force damage. --- 3. **Misalignment:** You take a −1 penalty to attack rolls with the weapon until recalibrated (1 day downtime). --- 4. **Unstable surge:** Once per long rest, the DM may trigger a mild wild arcane surge (setting-appropriate). --- 5. **Fragile construction:** The mod breaks after one combat (it can be repaired with 2 days downtime and half cost). --- 6. **Unexpected breakthrough:** The mod gains a cosmetic arcane enhancement (light, tone, rune glow, harmless effect). --- This table is intended to create tension and story hooks without deleting a character’s investment. --- --- . ## Upgrading a Base Gun Base guns may be reforged to higher rarity tiers, increasing their slot capacity. --- To upgrade a base gun: - You must possess a blueprint for the upgraded platform (or access to a faction workshop that does). - You must invest materials equal to half the difference in cost between tiers. - Downtime required: 5 days per rarity tier increased. --- Upgrading increases slot capacity but does not alter installed mods other than requiring them to be removed (DM discretion) if the refit process demands it. --- . ## Salvaging Mods A removed mod may be salvaged for materials. --- - Salvaging requires 1 day. - You reclaim materials worth 25% of the mod’s original value. --- Prototype mods require a DC 15 Intelligence (tools) check to salvage successfully. On a failure, the mod is destroyed during extraction. --- --- . ## Crafting Legendary Weapons Legendary modular weapons are not mass-produced. --- To craft a Legendary base gun, a character must: - Possess at least three Prototype blueprints. - Acquire at least one quest-tier rare material. - Spend 15 days of downtime. - Succeed on a DC 20 Intelligence (tools) check. --- On a failure, the project does not collapse, but you cannot attempt it again until you acquire additional rare materials or specialist assistance (DM discretion). Legendary crafting should feel like an event. --- \page # Chapter 5: Feats & Character Options These feats are designed to enhance modular firearm builds without breaking action economy, bypassing slot caps, or escalating damage beyond reasonable expectations. --- Unless otherwise stated, you may select these feats whenever you would normally gain a feat. These feats assume you are proficient with at least one modular firearm. --- --- . --- . ## Arcane Gunsmith You have mastered the engineering principles behind modular firearms. - Increase your Dexterity or Intelligence by 1, to a maximum of 20. - You reduce the downtime required to craft mods by 1 day (minimum 1). - When you clear a jammed weapon, you may do so as a bonus action instead of an action. - Once per long rest, you may temporarily suppress one drawback of one installed mod for 1 minute (DM adjudicates edge cases; this cannot remove slot limits or action economy limits). --- --- . ## Shock Trooper You specialise in close-range assault with modular firearms. - When you move at least 10 feet towards a creature before hitting it with a modular firearm attack, you gain a +2 bonus to the damage roll. This can occur once per turn. - When you hit a creature within 10 feet, you may push it 5 feet. This can occur once per turn. - You do not suffer disadvantage on ranged attacks made while within 5 feet of a hostile creature. --- --- . ## Voidline Sniper You excel at extreme precision. - Increase your Dexterity by 1, to a maximum of 20. - If you do not move on your turn, your first firearm attack that turn ignores half cover. - When you hit a creature at long range, you deal additional damage equal to your proficiency bonus. This can occur once per turn. - You have advantage on Wisdom (Perception) checks made to spot creatures beyond 100 feet. --- ## Runic Overclocker You push your weapon beyond safe limits. - When you hit with a modular firearm, you may deal an additional 1d6 damage. - When you do so, roll a d6. On a 1, the weapon jams after the attack resolves. - You may use this feature a number of times equal to your proficiency bonus per long rest. --- --- . --- . ## Battlefield Suppressor You specialise in tactical control. - When a target makes a saving throw against a control effect created by one of your mods (speed reduction, restrained, reaction denial, forced movement), it has disadvantage on that saving throw. - You may apply control effects from your weapon to two different creatures in the same round (still only one control effect per creature per round, per the mandatory lockout rules). - Once per long rest, when you successfully apply a control effect from a mod, you may increase its duration by one additional round. --- --- . --- . ## Elemental Channeler You channel elemental force through your weapon. - When you deal elemental damage with a modular firearm, you may reroll one damage die. You must use the new result. - When a mod changes your weapon’s damage type, you may switch it to a different elemental type during a long rest (fire, cold, lightning, or acid), provided you still obey the mod’s tier and restrictions. - Once per short rest, you may treat a creature as if it does not have resistance to your weapon’s elemental damage for one hit. --- --- . \page ## Arcane Quickdraw You are exceptionally fast with your weapon. - You add your proficiency bonus to initiative rolls while holding a modular firearm. - You may draw or stow your weapon as part of the same action used to attack with it. - When initiative is rolled, you may move up to 10 feet immediately. This movement does not provoke opportunity attacks. --- . --- . ## Rune Warden You have studied arcane inscription. - Increase your Intelligence by 1, to a maximum of 20. - When a rune mod requires a saving throw, increase its DC by 1. - Once per long rest, you may use a rune mod feature without expending its limited use. . . ## Design Notes on Feats These feats: - Do not grant extra attacks beyond the system’s limits. - Do not bypass slot caps. - Reinforce specialisation and identity rather than raw scaling. --- \page # Chapter 6: Example Builds These examples demonstrate how base platforms and modifications combine into distinct battlefield identities. Each build obeys the mandatory balance rules and showcases tactical specialisation rather than pure optimisation. --- Dungeon Masters can use these as NPC loadouts, treasure inspirations, or templates for faction armouries. --- --- . --- . ## The Storm Reaper **Rare Runeblade Carbine (3 Slots)** **Role:** Mobile battlefield pressure **Base Platform:** Runeblade Carbine --- **Mods Installed** - Stormcoil Barrel - Sentinel Frame - Bloodstone Magazine --- **Combat Identity.** This build thrives in mid-range engagements where mobility and sustained pressure matter. Stormcoil converts damage to lightning and adds an arc rider on critical hits. Sentinel Frame preserves threat when enemies close. Bloodstone provides reliable survivability through temporary hit points. --- **Strengths.** Sustained resilience; reliable mid-range damage; defensive tempo. --- **Weaknesses.** Limited long-range dominance; no area denial; relies on steady hits. --- --- . --- . ## The Phantom Line **Rare Voidline Sniper (3 Slots)** **Role:** Precision elimination **Base Platform:** Voidline Sniper --- **Mods Installed** - Sniper Frame - Snipeglass Prism - Phantom Round Circuitry --- **Combat Identity.** This build rewards patient positioning. Sniper Frame increases damage profile and long-range punch. Snipeglass Prism rewards staying still with advantage. Phantom Round Circuitry punishes enemies who rely on light fortifications. --- **Strengths.** Exceptional overwatch; strong counter-cover play; high opening accuracy. --- **Weaknesses.** Fragile in melee; dependent on terrain; minimal control tools. --- --- . ## The Iron Bastion **Very Rare Magebreaker Cannon (4 Slots)** **Role:** Anti-magic suppression **Base Platform:** Magebreaker Cannon --- **Mods Installed** - Nullfield Core - Heavybolter Assembly - Auto-Brace Bipod - Rune of Returning --- **Combat Identity.** Built to counter magical buffs and ranged threats. Nullfield punishes protected targets. Heavybolter increases damage and rewards holding position. Auto-Brace improves ranged defence. Rune of Returning prevents disarm-based counterplay. --- **Strengths.** Anti-magic pressure; strong ranged durability; high single-target threat. --- **Weaknesses.** Reduced mobility; limited crowd control; demands line-of-sight. --- --- . --- . ## The Wildfire Surge **Rare Scatterblaster (3 Slots)** **Role:** Close-range disruption **Base Platform:** Scatterblaster --- **Mods Installed** - Hexfire Coil Barrel - Flashburst Chamber - Tinker’s Counterweight Grip --- **Combat Identity.** This is a shock-weapon for corridor fights. Hexfire changes damage to fire and rewards critical hits with ignition. Flashburst creates a short-rest disruption moment. Counterweight keeps you functional in melee range. --- **Strengths.** Devastating in tight spaces; strong tempo disruption; excellent in ambushes. --- **Weaknesses.** Short effective range; exposes the wielder; struggles in open-field fights. --- \page ## The Revenant Choir **Very Rare Relic-Class Handcannon (4 Slots)** **Role:** Sustained necrotic execution **Base Platform:** Relic-Class Handcannon --- **Mods Installed** - Mortis Core Receiver - Cursebrand Etching - Bloodstone Magazine - Gyroscopic Stabiliser Stock --- **Combat Identity.** This build is designed for momentum. Mortis provides healing on kills. Cursebrand enables repositioning by disabling opportunity attacks on a key target. Bloodstone sustains through temp HP. Gyroscopic improves consistency through rerolls and prone advantage. --- **Strengths.** Strong sustain; stable accuracy; good target control windows. --- **Weaknesses.** Less burst; weaker into necrotic-resistant enemies; relies on finishing blows. --- . --- . --- . ## The Overclock Protocol **Legendary Stormreaver Rifle (5 Slots)** **Role:** High-risk, high-reward pressure **Base Platform:** Stormreaver Rifle --- **Mods Installed** - Overclock Frame - Arc Capacitor Core - Elemental Glyph Chamber - Void Echo Feeder - Runestone of Echoes --- **Combat Identity.** This build pushes the ceiling while still respecting restrictions. Overclock increases damage at the cost of jamming risk. Arc Capacitor creates a reload-cycle spike. Elemental Glyph adds controlled unpredictability. Void Echo Feeder improves reliability via limited-use advantage. Runestone ensures misses still generate value. --- **Strengths.** Strong accuracy spikes; layered tactical options; meaningful decision points. --- **Weaknesses.** Jam risk; resource tracking; higher complexity at the table. --- . --- . --- . --- . --- . ## Why Example Builds Matter These builds demonstrate: - Slot trade-offs - How restrictions preserve balance - Identity over stacking - Clear differences between sustain, control, burst, and precision --- Players should treat these as inspiration, not prescriptions. \page # Chapter 7: Legendary Signature Weapons Legendary modular firearms are one-of-a-kind weapons, each forged with a distinct origin and lasting significance. They are not simply tools of war, but defining pieces of a hero’s legacy. --- Every Legendary weapon follows standard slot limits, carries a single unique mythic trait, requires attunement, is rarely available for purchase, and is intended to stand as a narrative centrepiece within the campaign. --- ## The Black Eclipse **Legendary Stormreaver Rifle** **Requires Attunement** --- **Installed Mods** - Astral Piercer Barrel - Phantom Round Circuitry - Void Echo Feeder - Rune of Returning - Nullfield Core --- **Unique Trait: Event Horizon** Once per long rest, when you reduce a creature to 0 hit points with this weapon, you create a 10-foot-radius sphere of gravitational distortion centred on that creature’s space. Creatures of your choice in the area must succeed on a Strength saving throw or be pulled to the centre and knocked prone. The sphere lasts until the start of your next turn. --- **Lore.** Forged after a planar breach, The Black Eclipse was designed to eliminate threats that could not be contained by walls or wards. Its last wielder vanished beyond the Astral Sea. --- . ## Starfall Tyrant **Legendary Voidline Sniper** **Requires Attunement** --- **Installed Mods** - Sniper Frame - Stormcoil Barrel - Snipeglass Prism - Sigil of Time Dilation - Arc Capacitor Core --- **Unique Trait: Falling Star** When you score a critical hit at long range, radiant energy erupts from the target. Creatures of your choice within 10 feet of the target take radiant damage equal to your proficiency bonus. This effect may occur once per turn. --- **Lore.** Commissioned by a celestial order to eliminate threats before they reached sacred ground, its shots are said to fall like fragments of a dying star. --- ## Ashbringer Protocol **Legendary Magebreaker Cannon** **Requires Attunement** --- **Installed Mods** - Heavybolter Assembly - Hellsteel Drum - Alkahest Core - Runestone of Echoes - Auto-Brace Bipod --- **Unique Trait: Scorched Dominion** Once per turn When you deal fire damage: - Creatures resistant to fire take full damage instead. - Creatures immune to fire take half damage instead. --- **Lore.** Developed in response to creatures thought invulnerable to flame, its chamber never fully cools. --- ## Revenant Choir **Legendary Relic-Class Handcannon** **Requires Attunement** --- **Installed Mods** - Mortis Core Receiver - Bloodstone Magazine - Cursebrand Etching - Gyroscopic Stabiliser Stock - Rune of Returning --- **Unique Trait: Dirge of the Fallen** When you reduce a creature to 0 hit points, you may immediately move up to half your speed without provoking opportunity attacks. This movement does not count against your movement for the turn. Once per turn. --- **Lore.** Carried by a battlefield executioner who never spoke, each shot was said to echo like a distant chorus. --- ## The First Prototype **Legendary Arcanepistol** **Requires Attunement** --- **Installed Mods** - Overclock Frame - Elemental Glyph Chamber - Void Echo Feeder - Runestone of Echoes - Witchwood Handgrip --- **Unique Trait: Adaptive Matrix** At the end of a long rest, you may replace one installed mod with another mod you own without requiring downtime. Slot limits and stacking rules still apply. --- **Lore.** The foundation upon which all modular firearms were built. Some believe its design was discovered. Others believe it was given. --- \page # Chapter 8: Advanced Optional Rules These systems introduce elements of instability, escalation, and consequence into the modular framework. They are designed to add tension, reward calculated risk, and reflect the volatile nature of arcane engineering when pushed beyond safe limits. --- Such mechanics can heighten drama at the table, weapons may overheat, configurations may strain their limits, and power may come at a cost that extends beyond simple numbers on a sheet. In some campaigns, this reinforces a tone of experimentation and danger. In others, it may introduce complexity that distracts from the intended experience. --- Not every table requires escalation mechanics or instability rules. Select only those systems that align with your campaign’s tone, pacing, and narrative focus. Used thoughtfully, they deepen immersion and consequence. Used indiscriminately, they can overwhelm the core design. Balance them as carefully as you would the weapons themselves. --- . ## Heat & ## Overcharge System --- . ### Heat Points You gain 1 Heat Point when you: - Score a critical hit - Use a Prototype-tier mod - Force three or more creatures to make saving throws from a mod effect --- Heat resets to 0 at the end of a short rest. --- . ### Heat Threshold --- If your Heat Points exceed your proficiency bonus, at the end of your turn roll a d6. --- On a 1–2, the weapon overheats. --- . --- ### Overheat Effect When overheated: - You take 1d8 force damage - The weapon cannot be used until the start of your next turn - Heat resets to 0 --- . --- . --- . ### Overcharge Mechanic As a bonus action, you may Overcharge your weapon. Until the end of your turn, your next hit deals +1d8 damage. --- After resolving the attack, roll a d6. On a 1–2, the weapon jams. --- Once per short rest. --- ### Wild Arcane Discharge Table (1d8) When a jam occurs due to instability, the DM may roll: 1. Random elemental surge 2. 1d6 lightning damage to creatures within 5 ft 3. Teleport 5 ft in a random direction 4. 5-ft lightly obscured smoke 5. Next attack gains +1d4 damage 6. 1d6 psychic damage to wielder 7. Advantage on next attack 8. Perfect recalibration (no effect) --- ### Sentient Modular Firearms A sentient modular firearm has: - Alignment - Communication method - Desire - Conflict trait ### Strain System When the wielder refuses the weapon’s desire, gain 1 Strain. At 3 Strain: - The weapon may impose disadvantage on one attack roll (once per day), or - Trigger a minor arcane effect at DM discretion Strain resets when the desire is fulfilled. --- ### Corrupted Void Tech If a weapon contains two or more Void-themed mods, it becomes Corrupted. At the end of a long rest, roll a d20. On a 1, the wielder experiences a minor arcane corruption effect (narrative, not crippling). --- . ### Prototype Instability Escalation If a weapon contains three or more Prototype-tier mods, on a natural 1 attack roll: - The weapon jams - The wielder must succeed on a DC 15 CON save or fall prone --- \page # Chapter 9: DM's Integration Guide Modular firearms bring unparalleled adaptability to the field. They allow a wielder to adjust, refine, and respond to the shifting demands of battle with deliberate precision. A weapon can be altered to favour range over impact, control over chaos, subtlety over force. In the hands of the disciplined, such versatility becomes a strategic advantage, enabling solutions where rigid designs would fail. --- Yet adaptability without restraint invites imbalance. When every option is available, the temptation to pursue excess is ever present. Power must be measured, choices must be deliberate, and every modification carries consequence beyond its immediate effect. A change in range may cost stability, an increase in damage may demand greater focus or sacrifice elsewhere. No configuration exists in isolation. --- In mastering flexibility, one must also master balance. True strength lies not in stacking advantages without thought, but in understanding trade-offs, limitations, and intent. It is balance that transforms potential into control, and control into enduring power. --- . ## Establishing Tone Decide whether firearms are: - Rare relics - Emerging military technology - Standardised guild production - High-magitech commonplace equipment --- Availability shapes power perception. --- . ## Controlling Scaling Balance through: - Blueprint scarcity - Rare material requirements - Downtime gating - Attunement for Rare+ tiers --- Avoid granting early access to Prototype mods in low-level campaigns. --- . ## Encounter Adjustments If firearms feel strong: - Increase enemy mobility - Introduce layered threats - Add environmental constraints - Use resistance diversity --- Avoid simply increasing hit points. --- ## NPC Gunners NPCs may use simplified mod loadouts. --- **Arcane Marksman** - Sniper Frame - Snipeglass Prism - Longbite Barrel --- **Shock Trooper** - Scattershock Muzzle - Tinker’s Counterweight Grip - Bloodstone Magazine --- NPCs do not require full crafting rules. --- . ## Gradual Introduction 1. Introduce one base platform 2. Offer 3–5 Standard mods 3. Add Advanced mods later 4. Introduce Prototype mods as milestones --- . ## Preventing Abuse - Enforce slot limits strictly - Apply Control Lockout consistently - Monitor Prototype stacking - Gate rare materials narratively --- \page # Chapter 10: # Fighter Subclass - Arcane Artillerist Fighters who adopt this archetype blend disciplined martial technique with refined arcane engineering. Through study, experimentation, and battlefield experience, they learn to weave structured magic into their weaponry, enhancing function without sacrificing control. --- To them, a weapon is not merely steel and powder, but a calibrated instrument, tuned, modified, and perfected through careful design. Where other warriors rely on strength alone, these fighters apply precision, calculation, and arcane craftsmanship to dominate the field. --- . ## Level 3: Weapon Savant --- You gain proficiency with Tinker’s Tools. --- While wielding a modular firearm: - You may use Intelligence instead of Dexterity for attack and damage rolls. - You may clear jams as a bonus action. - Installing or removing mods takes 30 minutes. --- You learn one Standard-tier blueprint. --- . ## Level 3: Combat Calibration --- When you hit with a modular firearm, you may deal an additional 1d4 force damage. --- Uses equal to proficiency bonus per long rest. --- . ## Level 7: Tactical Overwatch --- When a creature you can see moves into a space within 30 feet of you for the first time on its turn, you can use your reaction to make one weapon attack against it. --- Once per round. --- . ## Level 10: Adaptive Engineering --- During a long rest, you may swap one installed mod with another you own. --- Once per short rest, you may automatically succeed on a saving throw caused by your weapon’s instability. --- . ## Level 15: Arcane Feedback Loop --- When you deal damage with a modular firearm, gain temporary hit points equal to your Intelligence modifier (minimum 1). This refreshes instead of stacking. --- . ## Level 18: Master of the Arsenal --- You may install one additional mod beyond your slot limit. --- This extra slot cannot contain: - A Prototype-tier mod - A mod that grants additional attacks --- Once per long rest, you may ignore the Critical Effect Limit for one attack. --- \page # Chapter 11: # Rogue Subclass — Hexshot Saboteur Hexshot Saboteurs specialise in the precise disruption of arcane forces. Through careful calibration and calculated strikes, they unravel enchantments, destabilise magical constructs, and exploit weaknesses others cannot perceive. --- Where many warriors meet magic with brute force, Hexshot Saboteurs dismantle it methodically. Their craft favours timing over spectacle and precision over excess, turning a single, well-placed shot into a decisive advantage on the battlefield. --- . --- . ## Level 3: Arcane Saboteur --- Gain proficiency with Tinker’s Tools (expertise if already proficient). --- When wielding a modular firearm: - You may use Intelligence for attack rolls (not damage). - Once per turn when you deal Sneak Attack damage, choose one: - Target cannot take reactions until start of its next turn - Target’s speed is reduced by 10 ft until end of its next turn - Target has disadvantage on its next Constitution save --- A creature can be affected by only one of these options per turn. --- . --- . ## Level 9: Disruption Specialist --- When you deal Sneak Attack damage to a creature concentrating on a spell, it has disadvantage on the first concentration check it makes before the end of its next turn. --- Once per short rest, when you deal Sneak Attack damage, you may suppress one magical effect on the target until end of its next turn (not artefacts or Legendary effects). --- . --- . ## Level 13: Phantom Positioning --- When you deal Sneak Attack damage, you may move up to half your speed without provoking opportunity attacks. --- Once per turn. --- . ## Level 17: System Collapse --- When you deal Sneak Attack damage, the target must make a Constitution saving throw. --- On a failure, choose one: - It is stunned until the end of your next turn (if below twice your rogue level in HP) - It immediately drops concentration - It takes additional force damage equal to half your Sneak Attack dice --- On a success, it takes damage equal to your proficiency bonus. --- Once per long rest. --- \page # Appendix A: Mod Summary Tables ## Barrel & Muzzle Mods | Mod | Tier | Key Effect | |-----------------------|-----------|--------------------------------------------------| | Longbite Barrel | Standard | +100 ft range, +1 at long range, −2 within 20 ft | | Stormcoil Barrel | Advanced | Lightning dmg, crit arcs (DEX save) | | Hexfire Coil Barrel | Advanced | Fire dmg; crit ignites (DEX save ends) | | Scattershock Muzzle | Standard | 15-ft cone (DEX save for half), AoE Mod | | Astral Piercer Barrel | Prototype | Ignores cover, crit banish (CHA save) | | Blunderbore Muzzle | Standard | 15-ft cone, half damage + push, AoE Mod | | Frostbite Barrel | Advanced | Cold dmg, hit reduces speed 10 ft | | Silencer Coil | Standard | Attack doesn’t reveal position by sound | | Phasewave Muzzle | Advanced | Push 10 ft (STR save), counts as control | --- . ## Frame & Receiver Mods | Mod | Tier | Key Effect | |----------------------|-----------|---------------------------------------------------------| | Repeater Frame | Advanced | +1 attack, extra hit can’t trigger runes/mags/SA | | Mortis Core Receiver | Prototype | Necrotic, heal on kill once/turn | | Stormrider Frame | Advanced | 30-ft lightning line 1/short rest, AoE mod | | Heavybolter Assembly | Standard | Base damage 2d10, advantage if stationary, −10 ft speed | | Sniper Frame | Standard | Base damage 2d12, +1d10 at long range once/turn | | Overclock Frame | Advanced | Damage die step up, jam on natural 1 | | Sentinel Frame | Advanced | Opportunity attacks with firearm in melee | | Arc Capacitor Core | Standard | First hit after reload deals +1d10 | --- . ## Stock & Grip Mods | Mod | Tier | Key Effect | |-----------------------------|----------|------------------------------------------------------| | Gyroscopic Stabiliser Stock | Standard | Reroll one weapon damage die, advantage while prone | | Witchwood Handgrip | Advanced | Mark target, +1d6 while marked, no concentration | | Clockwork Folding Stock | Standard | Concealment advantage, +1d6 vs surprised once/combat | | Tinker’s Counterweight Grip | Standard | No disadvantage in melee, advantage vs disarm | --- . ## Magazine & Power Core Mods | Mod | Tier | Key Effect | |-------------------------|-----------|-------------------------------------------------| | Alkahest Core | Advanced | Acid, −1 AC on hit (max −3) | | Elemental Glyph Chamber | Advanced | 1d4 rider, 1/turn, control counts lockout | | Void Echo Feeder | Prototype | PB/long rest advantage, +2 if already advantage | | Hellsteel Drum | Standard | Fire, ignore resistance, nat 1 hurts wielder | | Shattercharge Feed | Prototype | Crit: Con save or stunned, 1/long rest | | Bloodstone Magazine | Advanced | Temp HP = PB once/turn | | Nullfield Core | Prototype | Suppress one magic effect, 1/short rest | --- ## Scope Mods | Mod | Tier | Key Effect | |-----|------|-----------| | Tactical Lens Array | Standard | +5 passive Perception; initiative bonus; spotting advantage | | Snipeglass Prism | Advanced | If stationary, first attack has advantage | | Voidglass Scope | Prototype | See invisible + Ethereal within 60 ft | --- ## Rune Mods | Mod | Tier | Key Effect | |-------------------------|-----------|--------------------------------------------------------| | Runestone of Echoes | Advanced | On miss, PB damage to nearby creature 1/turn | | Sigil of Time Dilation | Prototype | Pre-initiative shot, 1/long rest | | Phantom Round Circuitry | Advanced | Shoot through 1 ft, cannot crit | | Cursebrand Etching | Prototype | No opportunity attacks on target 1 minute, 1/long rest | | Rune of Returning | Standard | Teleport weapon, 1/short rest | --- . ## Utility Mods | Mod | Tier | Key Effect | |-----------------------|----------|-----------------------------------------------| | Bayonet Spike | Standard | Bonus-action melee 1d6 | | Grapnel Launcher | Advanced | Mobility tool, 3/long rest | | Quick-Release Sling | Standard | Free draw/stow | | Smoke Discharge Valve | Advanced | 10-ft smoke, 1/long rest | | Flashburst Chamber | Standard | Blind burst, 1/short rest | | Auto-Brace Bipod | Standard | +2 AC vs ranged if stationary | | Shock Net Launcher | Advanced | Restrain, 1/short rest, control lockout | | Flare Beacon | Standard | Illuminate + reveal invisibility, 1/long rest | --- \page # Appendix B: Quick Reference . ## Mod Save DC Formula --- . --- **8 + Proficiency Bonus + Relevant Ability Modifier** --- . ## Crafting DCs | Tier | DC | |-----------|---:| | Standard | 14 | | Advanced | 17 | | Prototype | 20 | --- . ## Downtime | Tier | Days | |-----------|-----:| | Standard | 2 | | Advanced | 5 | | Prototype | 10 | --- . ## Slot Capacity | Rarity | Slots | |-----------|------:| | Common | 1 | | Uncommon | 2 | | Rare | 3 | | Very Rare | 4 | | Legendary | 5+ | --- \page # Modular Weapon Record Sheet --- ### Weapon Profile **Weapon Name:** _____________________________________________ --- **Base Platform:** _____________________________________________ --- **Rarity:** _____________________________________________ --- **Attuned?** ☐ Yes ☐ No --- **Damage:** _____________________________________________ --- **Range:** _____________________________________________ --- ### Installed Modifications | Slot | Modification |Tier | Mechanical Effect| Notes | |:----:|---------------|:---:|------------------|-------| | 1 | | | | | | 2 | | | | | | 3 | | | | | | 4 | | | | | | 5 | | | | | --- . ### Performance Tracking **Heat (Optional):** _______________ / Proficiency Bonus --- . **Special Traits / Mythic Effects:** __________________________________________________________________________________________ . __________________________________________________________________________________________ . __________________________________________________________________________________________ . __________________________________________________________________________________________ . __________________________________________________________________________________________ . --- . ### Configuration Notes Record tuning changes, recalibrations, or narrative upgrades below: __________________________________________________________________________________________ . __________________________________________________________________________________________ . __________________________________________________________________________________________ . __________________________________________________________________________________________ . __________________________________________________________________________________________ . __________________________________________________________________________________________ . . \page # Closing Statement Arcane Arsenal presents modular firearms as tools of deliberate design rather than linear advancement. Power within this system does not come from simple accumulation, but from considered choices made at the workbench and tested on the battlefield. Each component shapes the weapon’s behaviour. Every modification defines its role. Balance is not imposed from outside the system, it emerges from the trade-offs built into it. A modular firearm is crafted with intent. Its strengths are selected. Its limitations are understood. Over time, it becomes an extension of the character who built it, not because it is stronger than other weapons, but because it was shaped to serve a purpose. Use it thoughtfully. Build with intention. Let your design tell the story.