Arkane Crystal Rail Gun - Leg Prosthetic

You have a +1 bonus to attack and damage rolls made with this magic weapon.

Arkane Bullets The Crystal Railgun shoots elemental crystals as its bullets, which have unique effects based on the arkane powder that feeds it. YA basic arkane application is needed to be loaded for a crystal bullet to form, and they don't need special processing. This leg cannot be used as a firearm without loading components, such as arkane powder.

Red Arkane Deals 2d8 fire damage
Blue Arkane Deals 2d8 cold damage
Green Arkane Deals 2d8 poison damage
White Arkane Deals 4d8 thunder damage. If the attack hits, all creatures within 5 feet of the target must make a CON saving throw (save DC of user) or be knocked prone without taking damage.
Gold Arkane Deals 4d8 radiant damage. If the attack hits, all creatures within 5 feet of the target must make a CON saving throw (save DC of user) or be blinded without taking damage.
Black Arkane Deals 4d8 necrotic damage. If the attack hits, all creatures within 5 feet of the target must make a WIS saving throw (save DC of user) or be frightened of the target.
Yellow Arkane Deals 4d8 lightning damage and pierces 10 feet behind the target, all targets in the line of fire must make a DEX saving throw (save DC of user). A failed saving throw results in the same damage.

Longrifle: 
Properties - Reload 3 
Misfire 5 
Range 200/600 

Damage: 2d12+Dex Piercing + Arkane damage

It’s up to you to decide whether a character has proficiency with a firearm. Characters in most D&D worlds wouldn’t have such proficiency. During their downtime, characters can use the training rules in the Player’s Handbook to acquire proficiency, assuming that they have enough ammunition to keep the weapons working while mastering their use.

Notes: Bonus: Magic, Must wear gun as prosthetic to use., Damage, Combat, Range, Two-Handed, Ammunition (Firearms), Burst Fire, Reload, Slow