You create a 20-foot-radius sphere of acidic, transparent gas centered on a point you choose within range. The fog spreads around corners. It lasts for the duration or until strong wind disperses the fog, ending the spell. Its area is heavily obscured.

When a creature enters the spell's area for the first time on a turn or starts its turn there, that creature must make a Constitution saving throw. The creature takes 3d10 acid damage on a failed save, or half as much damage on a successful one. A creature that fails this save loses the ability to smell for a different amount of time depending on how long they remain in the sphere. A creature that remains in the sphere for only 1 turn suffers the effect for 1 round, a creature that remains in the sphere for 1 minute suffers the effect for 1 day, and a creature that remains in the sphere for 10 minutes permanently loses its ability to smell. A lesser restoration ends this effect. Creatures are affected even if they hold their breath, but are not affected if they do not have a nose or similar anatomical structure.

The gas moves 10 feet away from you at the start of each of your turns, rolling along the surface of the ground. The vapors, being heavier than air, sink to the lowest level of the land, even pouring down openings.

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the damage increases by 1d10 for each slot level above 5th.