Curse of Decay

You unleash a sickening curse on a creature. The target must succeed on a Constitution saving throw or become cursed.

When cursed, the target gains one point of exhaustion and loose 1d4 hit dice. While cursed, the target can't regian Hit Points and take 1d4 necrotic damage at the start of its turn.
At the end of each of its turns, the target can make another Constitution saving throw, ending the spell on a success.