This system treats guns as **customisable magic weapons** built from interchangeable parts. Instead of constantly replacing weapons, characters: - Upgrade a **base gun** - Install **mods** that change how the weapon behaves - Make meaningful tactical choices instead of stacking raw damage Think of it as: > **A magic item you build, not one you replace.** #### Core Concept > **A gun has a limited number of mod slots. > Each mod occupies one slot and alters how the weapon functions.** You can never exceed your gun’s slot limit, regardless of gold or crafting skill. #### Base Gun Models Before installing mods, you must have a **base gun**. |Rarity|Mod Slots|Description|Price (gp)| |---|---|---|---| |Common|1|Simple weapon with one enhancement|200| |Uncommon|2|Early customisation|750| |Rare|3|Strong, specialised builds|1,500| |Very Rare|4|High-end, multi-role weapons|4,000| |Legendary|5+|Signature, story-defining weapon|10,000| Note: **Mods are balanced primarily around slot limits, not gold cost.** --- #### Weapon Mods Each mod represents a **physical or magical component** of the weapon. Installing a mod permanently changes how the gun behaves until removed. > Installing or removing a mod requires **1 hour of work** and appropriate tools (DM discretion). Mods cannot be swapped during combat. ##### 🔹 Barrel / Muzzle Mods _Affect range, damage type, and shot behaviour._ |Mod|Effect|Price| |---|---|---| |Longbite Barrel|+100 ft range; +1 to attacks at long range; −2 to hit within 20 ft|400| |Stormcoil Barrel|Lightning damage; on crit, arcs to nearby target (Dex save)|800| |Hexfire Coil Barrel|Fire damage; on crit, target ignites (1d6 fire/turn, Dex save ends)|750| |Scattershock Muzzle|15-ft cone attack (Dex save for half)|500| |Astral Piercer Barrel|Ignores cover; on crit, banish target (Cha save)|1,200| |Blunderbore Muzzle|15-ft cone; half damage; targets pushed 5 ft|300| |Frostbite Barrel|Cold damage; hit reduces speed by 10 ft until end of next turn|700| |Silencer Coil|Attacks do not reveal your position on hit|600| |Phasewave Muzzle|Push target 10 ft on hit (Str save negates)|500| ##### 🔹 Frame / Receiver Mods _Define firing behaviour and damage profile._ |Mod|Effect|Price| |---|---|---| |Repeater Frame|Fire twice per action; second hit deals flat damage only and cannot trigger Sneak Attack, runes, or magazine effects|700| |Mortis Core Receiver|2d12 necrotic damage; regain 5 HP on kill|1,200| |Stormrider Frame|30-ft lightning line (Dex save); 1/short rest|950| |Heavybolter Assembly|2d10 damage; bracing grants advantage; −10 ft movement|700| |Sniper Frame|2d12 damage; +1d10 damage at long range|600| |Overclock Frame|+1 damage die; weapon jams on a natural 1|650| |Sentinel Frame|You may make opportunity attacks with this weapon in melee|800| |Arc Capacitor Core|First hit after reloading deals +1d10 damage|750| ##### 🔹 Stock / Grip Mods _Improve handling, stability, and posture._ |Mod|Effect|Price| |---|---|---| |Gyroscopic Stabiliser Stock|Reroll one damage die per attack; advantage while prone|400| |Witchwood Handgrip|On hit, applies _Hunter’s Mark_ (no concentration); bonus damage applies only to this weapon’s damage dice|800| |Clockwork Folding Stock|Advantage on Sleight of Hand to conceal weapon; surprise attacks deal +1d6 once per combat|250| |Tinker’s Counterweight Grip|Ignore disadvantage for ranged attacks in melee; +2 bonus vs disarm attempts|300| ##### 🔹 Magazine / Power Core Mods _Modify ammunition and sustained effects._ |Mod|Effect|Price| |---|---|---| |Alkahest Core|Acid damage; lowers target AC by 1 on hit (max −3)|900| |Elemental Glyph Chamber|On hit, roll 1d4 for bonus elemental effect|850| |Void Echo Feeder|Roll two attack dice and use the higher result|1,500| |Hellsteel Drum|Ignore fire resistance; on nat 1, weapon burns for 1d8 fire damage|650| |Shattercharge Feed|On crit, Con save or stunned for 1 round; 1/long rest|1,100| |Bloodstone Magazine|Gain temp HP equal to damage dealt (1/turn)|900| |Nullfield Core|Suppresses magical effects on hit for 1 round; 1/short rest|1,200| ##### 🔹 Scope Mods _Enhance awareness, targeting, and positioning._ |Mod|Effect|Price| |---|---|---| |Tactical Lens Array|+5 passive Perception; advantage on Initiative; advantage on Perception checks while aiming|400| |Voidglass Scope|See invisible and ethereal creatures within 60 ft|1,200| |Snipeglass Prism|Advantage on attacks if you remain stationary this turn|700| ##### 🔹 Rune Mods _High-impact magical effects._ |Mod|Effect|Price| |---|---|---| |Runestone of Echoes|On miss, half damage rebounds to nearby creature|1,000| |Sigil of Time Dilation|One surprise shot before initiative; 1/long rest|1,800| |Phantom Round Circuitry|Shoot through up to 1-ft-thick walls; cannot crit|1,400| |Cursebrand Etching|Target loses opportunity attacks for 1 minute; 1/long rest|1,800| |Rune of Returning|Teleport weapon to your hand; 1/short rest|800| ##### 🔹 Utility Mods _Add tactical options and tools._ |Mod|Effect|Price| |---|---|---| |Bayonet Spike|Bonus-action melee attack (1d6)|200| |Grapnel Launcher|Fire rope to climb or pull; 3 uses per long rest|700| |Quick-Release Sling|Draw or stow weapon as a free action|300| |Smoke Discharge Valve|10-ft heavily obscured smoke cloud; 1/long rest|600| |Flashburst Chamber|15-ft blind burst (Con save DC 13); 1/short rest|450| |Auto-Brace Bipod|Set up to gain +2 AC vs ranged attacks|400| |Shock Net Launcher|Restrain target (Dex save); 1/short rest|650| |Flare Beacon|Illuminate area and reveal invisibility; 1/long rest|350| --- #### Balance & Stacking Rules These rules are **mandatory**. ##### 1. Slot Limits - Each mod occupies **one slot** - Duplicate mods cannot be installed - Conflicting effects are resolved by the DM ##### 2. Attack Economy > **No more than one mod may grant additional attacks.** Weapons may never exceed normal action economy. ##### 3. Critical Hit Limits > **Only one critical-triggered mod effect may activate per turn.** The wielder chooses which effect applies. ##### 4. Control Lockout > **A target can suffer only one movement- or reaction-denying effect per round from mods.** Includes: - Speed reduction - Restrain - Reaction denial - Forced immobilisation ##### 5. Area-of-Effect Limit > **Only one cone, line, or AoE mod may be installed per weapon.** ##### 6. Repeater Restriction If a weapon fires more than once per action: - The second hit **cannot trigger runes or magazine effects** - Deals flat damage only unless otherwise stated #### Design Intent This system exists to: - Replace static +X weapons - Give martials meaningful progression - Encourage specialisation over optimisation - Create cinematic, tactical play Legendary weapons should feel **mythic**, not automatic.