The World of Velkacis
The Underworld is and has always been, it is just natural law. Velkacis is a land that was sequestered away, founded by Vernas who used their magic to protect the area and keep afflictions out.
A plague is afflicting the underworld which causes creatures to mutate as they suffer physically as well as in their mind, to the point where they can no longer comprehend their surroundings or remember who they once were.
Vernas magic is fading fast, and the once protected area known as Velkacis is shrinking rapidly as more fall victim to the affliction.