Arm Minigun

Your arm transforms into a minigun capable of shooting large streams of bullets, whilst transformed the gun is still considered part of your body and uses ammunition at a rate of 25 per attack.

Transform: morph or revert your off-hand into an active state you must consume 1 action, while your off-hand morphed you are unable to use objects or weapons that require use of your off-hand

Spin up/Spin down: Use a bonus action to spin-up, for the duration of which your movement is halved

This weapon can fire either as a cone or a line

Cone: This weapon fires a 30ft cone, anyone caught in the radius is rolled against as if it were a standard ranged attack using dex modifier to each targeted creature separately, if it hits the creature takes 3d6 piercing

Line:  This weapon fires a 60ft line, anyone caught in the radius is rolled against as if it were a standard ranged attack using dex modifier to each targeted creature separately, if it hits takes the creature 3d6 piercing

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: Afix this weapon to your arm this process takes 6 hours and proficiency with smithing tools, Damage, Combat, Range, Ammunition (Firearms), Reload