Armor of Iskander

An tenebrous magical force surrounds you, manifesting as a smoky shadow that covers you and your gear. 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 necrotic 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 necrotic damage increase by 15 for every two slots above 1st. When you cast this spell using a spell slot of 5th level or higher, creatures that take necrotic damage from this spell must succeed on a constitution saving throw or fall prone.