Fate's Eye Theatre: From the Edge of Oblivion
The physical manifestation of the sins of the world. The Corruption is both an idea and a force, both the creatures they represent and the disease it brings. Corruption is the end.
Each monster spawned of the surge is corruption, and there are many.
The land is blighted where ever Corruption stalks, and when cities are overtaken they become dead, spilling forth the vengeful corpses of those unfortunate enough to fall.
May God help us all.