Bunsen's Burner

You choose a point on a surface within range. A dull flame hovers a few inches from it, producing light equivalent to a candle. For the duration, if any gaseous effect crosses into the spell’s space, the burner immediately bursts into flame, consuming the entire connected region of gas that triggered the explosion. If the spell is cast inside an existing area of gas, it ignites immediately. When the gas ignites, each creature within 5 feet must succeed on a Dexterity saving throw or take 1d6 fire damage. Any creature in gaseous form automatically fails its saving throw and takes an additional 1d6 fire damage. Once the spell ignites an area, the spell ends.

The spell’s damage increases by 1d6 when you reach 5th level (2d6), 11th level (3d6), and 17th level (4d6).