Custic Gas

You create a 20-foot-radius sphere of pale-yellow mist centered on a point within range. The mist spreads around corners, and its area is lightly obscured. The mist lingers in the air for the duration.

Each creature that is completely within the mist at the start of its turn must make a Constitution saving throw or take 4d6acid damage. On a successful save, the creature takes half damage.

A moderate wind (at least 10 miles per hour) disperses theist after 4 rounds. A strong wind (at least 20 miles per hour) disperses it after 1 round.

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