Corrosive Cloudburst

You create a storm cloud above a point within range, which immediately bursts into a torrent of acid rain. Each creature in a 20-foot-high, 20-foot-radius Cylinder centered on that point makes a Dexterity saving throw, taking 10d4 Acid damage on a failed save or half as much damage on a successful one. Objects that are not being worn or carried also take this damage.

The acid dissolves earth and stone ground in the area into a mineral slurry to a depth of 5 feet, turning it into Difficult Terrain. Stagnant bodies of water are fouled, becoming undrinkable and dealing 1d4 Acid damage to any creature that ends its turn there. Both of these effects last until dried out or cleared by flowing water.

Using a Higher-Level Spell Slot. The initial damage increases by 2d4 for each spell slot level above 3.