Artificer's Arm (lvl 1)

Prepared spell. before activating the artificers arm you can prepare a spell from your spell list for it to cast once.

Arcane Familiar. the arm can be activated once every long rest for 1 hour at which point it is removed from your body and acts on its own. It takes its turn right after you and you may only use 1 arm while it is activated. The arm can be healed to full health with a mend spell, but if it drops to 0 hit points it is destroyed and you must spend 1 hours using smiths tools and 100gp of materials to make a new arm. The arm has an additional d4 (3) hit points per artificer level past level 1 and has your proficiency bonus

Armorers gauntlets. If you are an armorer the arm can use your gauntlet attack

Unarmed strike. Melee Weapon Attack: your proficiency bonus + your intelligence modifier to hit, reach 5 ft., 1 target. Hit: 1d4 + your intelligence modifier bludgeoning damage. 

Activate the artificers arm as a bonus action. The arm can reattach to you as a bonus action

Failsafe. If you fall to below 0 hit points the arm can reattach to you and you drop to 1 hit point instead