Cloudkill

You create a 20-foot-radius sphere of poisonous, yellow-green fog centered on a point you choose within range. The fog spreads around corners and its area is heavily obscured. It lasts for the duration or until strong wind disperses it. When a creature enters the area for the first time on a turn or starts its turn there, it must make a Constitution saving throw, taking 5d8 poison damage on a failure, or half on a success. The fog moves 10 feet away from you at the start of each of your turns.