Environment Para-Elemental Planes of Heat
Organization solitary, mass (2-4 swarms), or holocaust (7-12 swarms)
A heat swarm is a mass of flying, aggressive, foul-tempered elementals from the Para-Plane of Heat. A single heat elemental that makes up a heat swarm resembles a thumb-sized ball of fire with vaguely discernible facial features.
When encountered on the Material Plane (which is a very rare occurrence indeed), a heat swarm is most often found in a highly unbearable (by human standards) climate such as an active volcano.
Heat Swarm from the Tome of Horrors Complete, Copyright 2011, Necromancer Games, Inc., published and distributed by Frog God Games; Author Scott Greene.