Dragon Scales

A protective fire surrounds you, not hot to you, but a scorching heat to others. You gain 10 temporary hit points for the duration. If a creature hits you with a melee attack while you have these hit points, the creature takes 10 fire damage.

At Higher Levels. When you cast this spell using a spell slot of 3rd level or higher, both the temporary hit points and the cold damage increase by 5 for each slot.