Aura of Entropy

You create an emmanation of sickening energy that radiates out from you in a 30-foot radius. While the spell lasts, the sphere remains centered on you and moves with you. Each hostile creature in the sphere has disadvantage on saving throws against becoming frightened, paralyzed, poisoned, or stunned.

Creatures in the emmanation can't gain temporary hit points, and any effect that restores hit points to a creature has those hit points reduced by an amount equal to your spellcasting ability modifier (minimum of 1).