The Abyss is a empty place under all the Layers and Sub Layers, being a black void with no gravity. In here, Hell sends down the most powerful and dangerous creatures and humanoids, so they may never see the light of day ever again. However, there have been a few instances of these things being free, Two most notably being The Ancient Titan and Tronus. Overtime however, The Abyss corrupts a living creatures mind and body after a day in the Abyss, which the living creature goes in a state of hibernation. However, once they gain enough power, they can break free and escape.