Armor of Teslak

A protective magical force surrounds you, manifesting as an electrical aura that covers you and your gear. You gain 5 temporary hit points for the duration. If a creature hits you with a melee attack while you have these hit points, the creature takes 5 lightning damage.

At Higher Levels. When you cast this spell using a spell slot of 2nd level or higher, both the temporary hit points and the lightning damage increase by 5 for each slot.

(Teslak was a dwarven inventer who was testing the effects of electricity by flying a kite in a storm, too bad he forgot to take off his armor)