Corlon (Brain in a Robot Body)

Level Up. The following numbers increase by 1 when the adventuring party’s proficiency bonus increases by 1: Corlon’s skill and saving throw bonuses (above), and the number of hit points restored by his Repair action (below). When the party reaches 8th, 12th, 16th, and 19th level, one of his ability scores of his choice increases by 2, or two ability scores by 1. His ability scores can't be increased above 20 in this way.

Magic Transfer. When a member of the party wearing a Robo-Ring casts a spell, they can choose to instead store the spell in Corlon. He can then cast that spell once at will. If he casts the spell within 1 round, then he can cast it as a Reaction. Otherwise, the spell takes its usual Casting Time to cast. Corlon loses all stored spells when he takes a Short or Long Rest.   

Mendable. If the Mending spell is cast on Corlon, he regains 2d6 hit points. If he has dropped to 0 Hit Points within the last hour, a creature which is wearing a Robo-Ring and which has an Intelligence score of at least 16 can use their smith’s tools as an action to revive him, provided they are within 5 ft. of it and they expend a spell slot of 1st level or higher. He returns to life after 1 minute with all of his hit points restored.

Multiattack. Corlon makes two Bastard Sword attacks and one Shortsword attack. He can substitute one Shortsword attack for one Unarmed Strike attack.

Repair (3/Day). The magical mechanisms inside of Corlon restore hit points equal to 2d8+3 to himself or to one construct or object within 5 feet of him.

Bastard Sword. Melee Weapon Attack: +7 to hit, reach 5ft., one target. Hit: 9 (1d8+4) Slashing damage.

Shortsword. Melee Weapon Attack: +7 to hit, reach 5ft., one target. Hit: 7 (1d6+4) Slashing damage. 

Unarmed Strike. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 7 (1d6+4) Bludgeoning damage.

Cast Stored Spell. Corlon casts one spell stored in him by the member of the party wearing a Robo-Ring. This spell must have been stored in him no more than 1 round ago.