Nine Hells

The Nine Hells of Baator is an enormous plane of existence, and the origin of Devils in Dungeons & Dragons. This realm consists of nine demiplanes, or "circles", each one with its own physical laws and properties of matter, but all inhospitable to outsiders. Each of the Hells is ruled by an archdevil, the nightmarish landscapes a reflection of the evil that each ruler embodies.

Avernus
Avernus is the first layer of the Nine Hells and is the main battleground of the Blood war, ruled by Zariel. Avernus is the only layer of the Hells that can be accessed by planar portals. It is covered in ruins and jagged rocks. Toxic gas and a fiery red sky make up its atmosphere.

Dis
Dis is a barren landscape with filthy rivers and hills. Dis has a dull green sky with clouds and lightning. Ruins also dot the area from a time when the Blood war reached Dis. In the centre of this circle is the Iron City where the archdevil Dispater resides.

Minauros
The third layer of Baator is described as an endless swamp full of rot and decay. The landscape consisted of treacherous marshes full of dark, oozing mud, acrid waters and the bones of creatures whose flesh has long since rotted away. Rain and hail storms are frequent and fumaroles dotted about the landscape constantly spew sulphuric gas into the air. Within the bog of Minauros stands the city of Jangling Hiter, which is populated by kytons.

Phlegethos
Phlegethos best fits the common conception of Hell: a fire-blasted wasteland filled with rivers of lava and jagged, rocky peaks reaching up towards an ash-choked sky. The city of Abriymoch was the seat of power in this realm, built of hardened magma, obsidian, and crystal in the caldera of an extinct volcano which provided visitors some protection from the elemental environment found throughout the rest of the plane.

Stygia
Whereas Phlegethos is a plane of fire, Stygia is the exact opposite: an endless ocean dotted by great sheets of ice. The river Styx runs through here from Avernus, forming a channel through the ice. A few small islands made up the only un-frozen ground in Stygia, their peaks wreathed in lightning arcing from the coal-black sky. Where lightning struck, a strange phenomenon called "cold fire" erupted: white flames of extreme cold that "burned" for a short time and then disappeared without a trace.

Malbolge
There is significant disagreement between cosmologies on the nature of the sixth circle of Hell. As a Great Wheel layer, Malbolge was a gargantuan tumble of angular black stone blocks, each block ranging in size from a small city to a large metropolis, that formed a pile hundreds of miles thick. The randomly tilted and ill-fitting blocks were honeycombed with angular passages and caverns causing non-flying travelers to frequently need mountaineering skills and risk avalanches. Stinking clouds of vapour rose up from the depths and lit the sky with the colour of blood, causing cosmologists to speculate that the blocks of Malbolge may have rested on an infinite sea of lava. Corroborating reports have been heard of flammable materials left on the ground spontaneously combusting. Most habitations in Malbolge were copper-clad fortresses built from black stone.

Maladomini
The seventh circle is a twisted maze of ancient ruins filled with crumbling fortresses, dried-up streams and aqueducts, abandoned quarries and pits filled with dark ichor. Baalzebul, the ruler of this realm, was never satisfied with the construction of the cities under his domain, repeatedly commanding his subjects to abandon them and then rebuild elsewhere. Currently, the city of Malagard stands as a beautiful, shining beacon amidst the abortions of Baalzebul's fickleness.

Cania
Cania is a frozen wasteland ruled by the archdevil Mephistopheles. The glaciers of this Hell moved with unnatural speed and the temperatures consistently remained at −51 ℃. If there is any upside to this, it is that travellers through this realm will most likely die from the intense cold rather than become victims of the few devils and other creatures that reside here.

Nessus
The lowest level of Baator was a land of extremes: some areas were as cold as Cania while others were as infernally hot as Phlegethos. Within the blasted centre of this Hell stands the citadel of Malsheem, home to millions of devils and the supreme ruler of the Nine Hells himself, Asmodeus.