CAUSTIC SPHERE

A roiling ball of corrosive acid streaks from your fingertip to a point you choose within range, then erupts in a 20-foot radius sphere. Each creature in that area must make a Dexterity saving throw against your spell save DC. A creature takes 8d6 acid damage on a failed save, or half as much on a successful one.

The acid lingers. Any creature that failed its save takes an additional 2d6 acid damage at the start of its next turn as the corrosive substance continues to eat through armor and flesh.

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