Atrophy

As an action, you make a melee spell attack against a creature you can reach. On a hit, the target takes 10d10 necrotic damage and must make a Constitution saving throw. On a failed save, the creature gains 1 level of exhaustion as their muscles begin to break down and they become weakened by the spell. This exhaustion can only be reduced by taking a long rest or a spell powerful enough to reduce exhaustion, such as a greater restoration or wish spell. 

At higher levels: When you cast this spell using a spell slot of 8th level or higher, the level of exhaustion suffered increases by 1.