Corrosive Venting

You can control causticity as you vent your gases. When you Vent Gas, increase the area of your emanation to 10 feet. You can choose to make the gas you vent caustic. If you do, any non-barathu creature that enters the emanation or starts its turn in the area takes 3d6 acid damage, with a basic Reflex save against your class DC or spell DC, whichever is higher. On a critical failure, a creature additionally takes 1d4 persistent acid damage. At 17th level, the acid damage increases by 2d6, and the persistent acid damage increases by 1d4.