Thunder Dragons are the masters of electricity. Their wings gather energy as they soar through the clouds, and when they clap their wings together they can create devastating arcs of lightning. They can stay airborne nearly indefinitely, landing only to sleep and breed; they catch their prey from the air and take moisture from the clouds. A thunder dragon’s roar is considered to be an omen of misfortune.

Dragons are highly-intelligent reptilian creatures that—from a human perspective, at least—appear to live forever. Many different varieties of dragon exist, each with their own unique qualities, habitats, and behavior. Adolescence in dragons is usually marked by the growth of a hatchling’s wings, although not all breeds of dragons grow wings and some breeds have other traits that indicate the beginning of maturation. In Galsreim, dragons and humans coexist peacefully.

Thundarus is one of the most feared dragons in his master's cave.  He is capable of producing electricity at will within a 500 foot radius, and the electric shock he generates can take form from mere static to a devastating bolt of lightning capable of turning targets into an insignificant pile of ash.  Thundarus is proud and powerful, and shows it by creating vast thunderstorms whenever and wherever he flies.

He has a rather fearsome reputation, but upon inquiry of other dragons, it is revealed that Thundarus is fierce towards enemies not because they threaten his personal safety, but because they threaten the safety of the fellow dragons he lives with in his master's cave.