Armor of Ajax

You channel the power of Ajax, the Storm Captain of Greybank. 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.