Tidal Time

Targeting a creature within range, you force them to make a Wisdom saving throw; on a failed save their body begins to experience time at a much faster rate. On a failed save they suffer on level of exhaustion. At the beginning of each of their subsequent turns they must repeat this saving throw or suffer one additional level of exhaustion for each failed save. 

If a creature succeeds on three of these saving throws, the spell ends on them; if they succeed on the initial saving throw the spell has no effect whatsoever. Levels of exhaustion persist after this spell ends.

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the number of creatures you can target increases by 1 for each slot level over 3rd.