Malzyxia, The Unhallowed Realms

Below the surface of Eko, and stretching around the world in all directions, lies Malzyxia, the Unhallowed Realms. No one knows how deep it goes, but everyone is certain that it is a place of powerful evil. When the world was being created, it is said that Zyxus's uncorrupted head, Xus, could not watch while the first layers were being built around the stone, at risk of utter corruption like his twin. And so, it was only Zyx who designed and channeled the evil of the stone to make this world beneath the surface. Named Malzyxia, after the evil side of Zyxus, few from the surface dare to go further than a few miles into the subterranean maze of tunnels. As you get deeper, the gods' ability to hear and answer one's prayers fade away, as they are blocked by the miles of corruption that lie between you, and disrupted by the evil aura of the Absinthe Stone. In the depths of Malzyxia, there are no gods one can pray to, and so its inhabitants have been called the Godless Ones. These include mind flayers, aboleth, drow, duergar, darklings, and many other manners of evil creatures.