Bone Armor

The bones of a dead creature magically surround you, manifesting with a spectral mist around them as they cover you and your gear from harm. You gain 10 temporary hit points for the duration and your AC becomes 15. If a creature hits you with a melee attack while you have these hit points, the creature takes 10 necrotic damage. 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 4th level or higher, both the temporary hit points and the necrotic damage increase by 10 for each slot.