You can use acid magic to create caustic vapors.
Prerequisite: Able to cast 3 spells that deal acid damage
Benefit: You can cast spells that deal acid damage as “caustic spells,” creating a cloud of burning vapor around any target that suffers a direct hit, spreading the acid damage over a slightly larger area of the target. Only spells that allow a saving throw and deal acid damage can be caustic spells, and the save DC of a caustic spell is 1 lower than normal (because the acid is spread over a larger area in order to create a cloud of vapor). When you cast a caustic spell, any target that fails its save against the spell is engulfed in a thin cloud of stinging vapor.
Targets engulfed in the vapor from a caustic spell have difficulty seeing, hearing, or smelling targets. For the duration of the vapor, targets treat all other creatures as having 20% concealment. This effect lasts 1 round for every 3 levels of the caustic spell (minimum 1 round). Targets with blindsense and those immune to acid damage are immune to this added effect.
Adventurer’s Handbook: Genius Guide Volume 1. Copyright 2010, Super Genius Games. Authors: Owen K.C. Stephens and Stan!