Vapor rat

Vapor rats were a creature that resembled gray-furred giant rats, but were connected to the element of air.

Biology
In their normal, physical state vapor rats were very fast. They were also adept at swimming and could rapidly burrow through loose soil.

Abilities
Vapor rats were able to alter their physiology, transforming into a gaseous form that resembled the wisps of a cloud or similar vapors. In this state they were able to steer their bodies through wind, granting them a form of flight.

These creatures always assumed this gaseous form whenever they felt seriously threatened or were injured. When in this form they could only be harmed by means of magical fire or lightning, as well as exceptionally strong winds.

Whenever a vapor rat was killed or seriously wounded a small cloud of noxious fumes would emanate from their bodies, similar to the spell stinking cloud. They always directed the release of this gas, having it affect a particular target. Beyond this gas dissipated.

Combat
Vapor rats typically attacked other creatures with their sharp teeth whenever they were angry, hungry, or cornered.

Diet
Vapor rats were an omnivorous species. They equally loved to feast upon trash and carrion.

Habitats
In Faerun they could be found in the Daggerdale region and some of the medium woodlands of Cormanthor, including the Border Forest and Vale of Lost Voices. They also inhabited the clouds upon which cloud giant castles rested as well as clouds inhabited by cloud dragons. Beyond Toril, they could be found on the planet Oerth.

Outside of the Prime Material plane, vapor rats could be found in the Elemental Plane of Air, the Quasi-Elemental Plane of Steam, and the Para-Elemental Plane of Smoke. On the Elemental Plane of Air they often lived alongside genies, who considered them to be pests.

Relationships
Smoke mephits often kept vapor rats as pets, prizing them as many creatures would a cat.

Usage
The bottled dust of three vapor rats could be used as an alternative ingredient in crafting a potion of gaseous form. The blood of a vapor rat could mixed with the blood of a green dragon in a broth to enchant its tooth.