Call of the Grave

Your spell causes black tendrils of negative energy to grasp the targets, draining the very life from them. Choose up to three creatures within range. Those creatures make a Wisdom saving throw, on a failure each target's hit point maximum decreases by 5 for the duration, and they take 5 necrotic damage at the end of each of their turns for 5 rounds.

At Higher Levels. When you cast this spell using a spell slot of 3rd level or higher, a target's hit points decrease by an additional 5 for each slot level above 2nd.