Vitality Drain

You bestow a baneful curse that saps the life out of a target you can see in range. Make a melee spell attack and on a hit, the target is cursed. The target must make a Constitution saving throw at the beginning of each of its turns. On a failed save, the target takes 6d8 necrotic damage and gains 1 point of exhaustion. If the target succeeds 3 of these saves, the spell ends. While cursed in this way, the creature cannot regain hit points in any way, but if the creature is subjected to healing it gains advantage on its next Constitution saving throw made to resist this spell. A creature killed by this spell is drained of all life energy and can only be restored to life by means of a true resurrection or wish spell.

The spell can be dismissed by a remove curse spell cast at 7th level or higher.