Bannegan's Mudball

A trail of muck flies from your pointing finger to a point you choose within range and then shudders with a low burble into a swallow of muck. Each creature in a 15-foot-radius sphere centered on that point must make a Dexterity saving throw. A target takes 4d6 force damage and is restrained on a failed save, or half as much damage on a successful one and isn't restrained

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the damage increases by 1d6 for each slot level above 3rd.