Demi

You sling a bolt of deprecating energy at a creature of your choice. The creature must make a Constitution saving throw. On a failed save, its maximum hit points are reduced by
one quarter.
At the end of each of its turns, the creature can make another Constitution saving throw. On a success, the spell ends on the creature.
Higher Level Casting. When you cast this spell using a spell slot of 9th level, its maximum hit points are instead reduced by half. This effect lasts until dispelled.