Cloud of Pestilence (C)

You create a heavily obscured 15-foot radius sphere of
green fog centered on a point you can see within range.
The fog spreads around corners but is stationary and
lasts the duration unless dispersed by a strong wind (at
least 20 miles per hour), which ends the spell after 1
round.

When a creature first enters the cloud or starts its turn
there, that creature must make a Constitution saving
throw or take 4d6 poison damage or half as much on a
successful save. Creatures are affected even if they hold
their breath or don’t need to breathe.

At Higher Levels. When you cast this spell using
a spell slot of 5th or higher level, the poison damage
increases by 1d6 and the radius increases by 5 feet for
each slot level above 4th.