Corban's warding rings

A protective magical force surrounds you, manifesting as a spectral ring that orbits you and your gear. You gain 5 temporary hit points for the duration. As a bonus action on each of your turns thereafter — you can expend a number of the rings, sending them streaking toward a point you choose within 60 feet of you. Make a ranged spell attack. On a hit, the target takes 5 points of force damage per ring. You lose 5 temporary hit points when you expend a ring. When all rings have been expended the spell ends. At Higher Levels. When you cast this spell using a spell slot of 2nd level or higher, you gain an extra ring, increasing the temporary hit points by 5.