The Infernal Insurrection

The Infernal Insurrection, or the Third Infernal Emergence, denotes a period of chaos throughout the Ten Hells and the outer planes after the River Styx dried up. Most notably it involved a war between the Ten Hells and Mt. Celestia, destabilization throughout ever layer of the Ten Hells, and the disappearance of Demons and the Abyss.