The strongest version of a Rotworm, it seems to spawn randomly in Rotworm and Carrion Worm Caves.
The Sacred Casket (Book) says that the substance inside the Jewel Case (Nomad) can potentially attract these creatures, as it has already proven to attract regular Rotworms and Carrion Worms. This is a reference to the Dune series of books wherein desert-dwelling sandworms, on which rotworms are based, are heavily attracted to melange spice.
Damage Taken From Elements
No strategy needed. Treat it like a Carrion Worm. Recommended to be level 16 before trying to kill one.