The Shizaiian Plane is the lowliest of the Three Planes.
The gods of old waged war on each other, and the losing side was forced to the Shizaiian Plane. There, the gods schemed and plotted to exact their revenge on their fellow gods. They created demons and devils out of lost souls, and let them loose on the Kaunon Plane in order to kill all the mortals that the other gods held so dear.
Souls are drawn to the Shizaiian Plane by promises of immortality and power; those who fall for the temptation are snatched up by the evil gods and made into demons. Souls caught and used to fuel the evil demons can never escape their fate once made into the monstrosity. When demons die, the trapped soul is sent back to the Shizaiian Plane, instead of the Vault of Eternity, and formed into another beast of destruction.