Armor of Resonate Aegis

You weave a geometric lattice of humming arcane force around yourself. The air around you vibrates with contained power, you gain 5 temporary hit points for the duration. If a creature hits you with a melee attack while you have these temporary hit points, the creature takes 5 thunder damage as the aegis releases a punishing shockwave.

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