Caustic Payload

You clench your fist and strike it downwards, causing a mote of caustic liquid to appear in midair and strike the ground, splattering in a roughly 10-foot-radius circle of burbling acid that coats the ground. Each creature within that area when the acid bursts must make a Dexterity saving throw.

On a failed save, a creature takes 8d4 acid damage, or half as much on a successful save. Any creature that enters the pool of acid, or starts it's turn there takes 4d4 acid damage. 

The acid-coated surface counts as difficult terrain.

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the initial damage increases by 2d4, and the damage of the acid pool increases by 1d4 for each level above 3rd.