Aesop's Arcing Aegis

You vibrate your own electric energy, and a protective aura of lightning surrounds you, as electricity that harmlessly wreaths 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. If the target is wearing armor made of metal or is drenched in water, they take 10 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 level above 1st.