Baator

Baator, often referred to as the Nine Hells of Baator, the Land of Broken Promises, or simply as the Pit, is the plane where Law bonds itself to Evil in a sometimes uneasy alliance of foul politics and corruption. It is the home plane of the Baatezu, who dominate the plane utterly. Other diabolic species include imps, kytons, bezekira, and hell hounds.

Baator's nine layers exist metaphysically in the shape of an inverted mountain, with the layer of Avernus at the "top," bordering Gehenna, Acheron, the Outlands, and the Astral Plane. "Beneath" it are, in order, iron Dis, swampy Minauros, fiery Phlegethos, icy Stygia, treacherous Malbolge, ruined Maladomini, the frozen waste of Cania (or Caina), and Nessus. Nessus is the deepest and darkest of the nine hells, a place of yawning chasms and the home of the Dark Eight, a council of nine pit fiends in charge of the eight bureaucracies that control the lawful side of the Blood War and baatezu life. Greater than them are the diabolic nobles serving the Dark Lord of Nessus, a mysterious being sometimes called Asmodeus.

Each of Baator's other layers is also ruled by a Lord of the Nine, with a staff of nobles serving the lord's interests on the layer. The Lords of the Nine care little for the Blood War or the baatezu, concentrating on establishing cults of worshippers on other planes and on elaborate games of politics and espionage as they seek to dominate and overcome one another.