Baator

The Nine Hells of Baator is an Outer Plane, and the birthplace of devils. Filled with smoke, fire, and ash, each Hell save the first is buried deeper underground. These continent-sized caverns contain fiery infernos, frigid wastelands, poisonous mires, and cruel fortresses, all of which are terrible beyond understanding. Only the greatest - and most foolhardy - adventurers dare to venture into this plane.

The Nine Hells

Baator is divided up into nine descending layers, each contained within a massive cavern beneath the layer above it. Each layer is ruled by an Archdevil, a powerful devil akin to a demigod. There is a strict heirarchy between them, with each layer being subordinate to the one below it.

Avernus

The surface layer of Baator, Avernus is a blood-soaked rocky wasteland. Jagged mountains make navigation difficult, while fireballs rain from the sky. Avernus has long been one of the primary battlefields of the Blood War between devils and demons, and the remains of innumerable armies coats the landscape. Through the center of the realm runs the River Styx, whose waters rob all who touch it of their memories. Avernus has been alternately ruled by the pit fiend Bel and the fallen angel Zariel, who dwell in an imposing fortress known as the Bronze Citadel. Both have ever been fierce generals dedicated to winning the Blood War at all costs.

Dis

Beneath Avernus lies the city of Dis, a veritable maze of narrow alleyways between buildings of black iron whose layout constantly shifts and changes. At its center is the Iron Tower, from where the archdevil Dispater oversees mining and smelting operations that produce countless infernal weapons for him to sell to the highest bidder.

Minauros

An oil rain perpetually falls upon Minauros, a massive, festering swamp whose foulness assaults all the senses. Much of the layer is dominated by the Sinking City, which is constantly built up even as it sinks inexorably into the mire beneath it. It is here that the souls of mortals are bartered and traded and various Batirian dukes vie for the favor of the miserly Mammon, the serpentine archdevil who controls it all.

Phlegethos

The fiery cavern of Phlegethos is a constant inferno of heat and flame. The air is a choking cloud of noxious fumes, the rivers and lakes are boiling lava, and jets of fire burst from countless fissures in the volcanic rock. Those mortals who have survived the journey describe the fire as not being truly random, but rather actively seeking them out. The blasted landscape is dominated by the palace ruled by Lady Fierna and her father, Belial, who adjudicate the complicated laws governing the various contracts and agreements originating in Baator and administer what passes for justice in Hell.