(air, elemental, extraplanar)
Source: The Emerald Spire Superdungeon, pg(s). 153
A caustic stalker resembles a hissing cloud of foul-smelling gases with reaching hands and a fierce, eerie visage.
Caustic stalkers originate in pockets of poisonous gas in the Plane of Air, but usually leave their birthplaces to congregate in places of great heat and pressure, like the cores of Material Plane worlds, or the border between the Plane of Fire and the Plane of Earth. They are usually content to drift amid the searing rocks and toxic fumes, but sometimes emerge into more spacious areas where they become short-tempered, especially in windy areas.