Black Rain

You create clouds of billowing death in a wall that is 30 feet long, 10 feet high, and 1 foot thick. Creatures in the area must make a Constitution saving throw, taking 4d4 necrotic damage on a failed save, or half as much on a successful one. A creature takes the same damage when it enters the wall for the first time on a turn or ends its turn there.

Water in this area is considered undrinkable if rain mixes with it.

At Higher Levels. When you cast this spell using a spell slot of 3rd level or higher, the damage increases by 1d4 for each slot above the 2nd, and the length and height of the spell increases by 5 feet for each slot above 2nd.