Tales of Tolgard
Fire bats are elementals, native to the Plane of Fire; unlike fire elementals, however, they are not composed solely of fire. They can fly through the flames of magma as easily as normal bats fly through the air. They propel themselves not so much by aerodynamics as the hot gases they expel from their tubes within their body, only using their wings to steer.
A fire bat cannot enter water or any other non-flammable liquid. A body of such liquid makes an impassable barrier unless the bat can step, jump, or fly over it.
Fire bats feed on living creatures, attacking such targets and devouring their bodies until they are satisfied. When full, the bat has a 25% chance of dividing through asexual fission in the next 24 hours.
Their bodies are about two feet long with a four foot wingspan. They burn continuously with an unbearably hot, red flame that makes it look larger than it is. Until it dies and cools, it is impossible to distinguish from mundane fire.
Fire elementals get along well with these bats, but salamanders, efreet, and most other creatures of fire prey on them. This is an important check on their population, since they not only regenerate but will also multiply where food is plentiful. Without any natural predators, they would over run the entire Plane of Fire within weeks.