You attempt to drain the life force from one creature of our choice within range. A beam of dark energy leaves them, flowing into your hand. The creature must succeed on a constitution saving throw or suffer one level of exhaustion. At the start of each of their turns while effected by this spell, they must succeed on this throw again or take another level of exhaustion. On a successful save, the spell ends.
Each time the target takes a level of exhaustion, you grow more powerful, gaining various bonuses:
1 - You have advantage on all ability checks until you finish a long rest
2 - Your speed increases by 10 ft until the spell ends
3 - You have advantage on attack rolls until the spell ends
4 - You gain a number of temporary hp equal to 1/4 the targets total hp
5 - Your speed is increased by another 10 ft until the spell ends
6 - You regain all lost hit points
At Higher Levels: When you cast this spell with a spell lot of 9th level, the target takes 2 levels of exhaustion upon failing their initial save.