Arcing Armor

You touch a willing creature who isn’t wearing armor, and a crackling shell of sparks surrounds it until the spell ends. The target gains resistance to lightning damage. When the target is hit by an attack from within 15 feet, the shell lashes out with a whip of lighting that deals 1d8 lightning damage to the attacker. The spell ends if the target dons armor or if you dismiss the spell as an action.

At Higher Levels. When you cast this spell using a spell slot of 2nd level or higher, the whip will lash out at one additional target within range per level, to a maximum of 4.