Astral Slayer

Astral Slayer.
Found by a crashed spell jammer inside a box with an emblem resembling a cog the only data pretraining to the origin of these weapons seems to be lost to the void
When used to make a ranged attack you inflict 2d6 + your Intelligence modifier. lighting damage.

Supernatural Fear. Once per long rest you may use the Supernatural Fear cantrip, after a hit, to target a creature. The creature must succeeded a DC 15 Wisdom saving throw or be Frightened until the end of the creature's next turn.

Slayer Chainsaw. You create a matching blade to accompany your firearm, rendering you a deadly opponent in both melee and ranged combat. You may use an action to cast the spell Slayer Chainsaw. The attack roll uses your Intelligence modifier, and you are proficient with the attack. On a hit, the attack deals slashing damage equal to 1d6 + your Intelligence modifier.

Misfire (1). Whenever you make an attack roll with a firearm, and the dice roll is equal to or lower than the weapon’s Misfire score, the weapon misfires. The attack misses, and the weapon cannot be used again until you spend an action to try and repair it. To repair your firearm, you must make a successful Tinker’s Tools check (DC equal to 8 + misfire score). If your check fails, the weapon is broken and must be mended out of combat at a quarter of the cost of the firearm. Creatures who use a firearm without being proficient increase the weapon’s misfire score by 1.

Curse. This pistol is cursed, and becoming attuned to it extends the curse to you. Until the curse is broken with Remove curse or similar magic, you are unwilling to part with the pistol, keeping it within reach at all times. And when the weapon misfires the chain-blade dislodges dealing 3d6 + your Intelligence modifier to a random creature within 60ft.

Attuning to this item gives the player the cantrips Slayer Chainsaw and Supernatural Fear.

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: Replace Damage Type: Lightning, Weapon Property: Two-Handed, Bonus: Magic Item Attack With Intelligence, Artificer, Cursed, Range, Ammunition (Firearms), Reload