uncommon evocation poison 

Traditions arcane, primal

Cast [>>] verbal, somatic

Range 30 feet; Area 10-foot burst

Saving Throw basic Fortitude; Duration sustained up to 1 minute

With a rattling hiss, you create a quickly evaporating mist of invisible poisonous marsh gas to smother creatures in the area. When you Sustain the Spell, the mist dissipates completely from the previous area, and you can select a new area within range to fill with the mist. If you don't Sustain the Spell, the mist dissipates and the spell ends. You deal 4d6 poison damage to each breathing creature that starts its turn in the area. Each affected creature must attempt a Fortitude save. The creature is then temporarily immune to gasping marsh for 1 minute.

Critical Success The creature is unaffected.Success The creature takes half damage.Failure The creature takes full damage and is sickened 1.Critical Failure The creature takes double damage, is sickened 2, and takes 1d8 persistent poison damage.

Strength of Thousands #3: Hurricane’s Howl, page 77.