Copper

Experimental, electrically powered battle armour. Every time copper makes an attack, roll a d4, on a two or less, any bonus to attack becomes negative, and copper takes a d4 of lightning damage. If copper is removed from his battle armour, he becomes a regular human with no abilities.

Overload. Copper is immune to all lightning damage that does not exceed 15, if more than 15 points of lightning damage is done to copper in a turn, his battle armour enters an overloaded state for a turn, in which it loses all functions. This will also occur if he rolls a one on any attack.

Experimental tech. Due to the nature of copper's battle armour, it is susceptible to malfunctions and breaks, at the start of coppers turn, and every time a successful attack is landed on copper, roll a d20, on a 5 or lower, one of the battle armour's functions becomes disables for the rest of the fight.

Conductor deployment. Deploys four conductor drones, for every conductor drone, Copper's attacks deal and extra point of lightning damage. The conductor drones are small, have an AC of 10, a movement speed of 15ft, have 5 hit points, and must have no obstacles between them and Copper to apply their effect.

Electrified knuckle dusters. Melee Weapon Attack: +3 to hit, reach 5 ft., 1 target. Hit: 1d4 bludgeoning damage and 1d4 lightning damage. 

Conductive stake. Ranged Weapon Attack: +2 to hit, range 30 ft., 1 target. Hit: 1d4 piercing damage, and the stake embeds itself in the target, it takes a bonus action to rip out the stake, and the creature will take a point of damage.

Electrical connections. If a creature within 10ft of copper has a conductive stake in them, they take 2 points of lightning damage.