Source: Escape from the Prison Moon, pg(s). 55
A radiation drake's skin is dark, most often dull green or black. Its teeth and the spikes running the length of its spine are bright crystalline, which glow white-hot when the drake unleashes its radioactive fire breath weapon. It possesses a long neck, long tail and only four limbs: a pair of wings and two powerful hind legs. A typical radiation drake is 15 feet long and weighs 1000 pounds.
Radiation drakes are found on planets with extensive radioactivity or the presence of kaiju; it is unknown if there's a link between kaiju and radiation drakes. Radiation drakes and kaiju typically ignore each other or more rarely enter symbiotic relationships: the drake feeds on the kaiju's parasites, cleans up after their kills, or protect young kaiju from predators. It's hypothesised that radiation drakes are the offspring of a dragon kaiju, but there's little evidence for this. Radiation drakes can speak Draconic and are capable of planning but usually act out of instinct.