Mad Destroyers are the fallen Ratkin
The Wyrm is insane and hates the Weaver for ensnaring it in her web. Both its madness and its loathing of the Weaver give it common cause with at least some wererats. Ratkin are prone to madness and many of them consider the Weaver to be an even greater threat than the Wyrm. The rulers of most Ratkin nests wish to build up their numbers before they strike at humanity, and are content that the Apocalypse will arrive soon enough. A few wererats have grown tired of waiting. The ones who glory in the idea of watching the entire world burn, or who fixate on plans to destroy humanity sometimes find like-minded allies among the legions of the Wyrm. Thurifuge, the Maeljin Incarna of disease, takes the most interest in recruiting Ratkin. He finds work for most of them in his Duchy in Malfeas, where they create ever more deadly plagues. He also assigns some of them to work in Pentex medical research facilities back on Earth.
- W20 Book of the Wyrm, p. 163-164