Nine Hells

In the Forgotten Realms campaign setting, Baator, also known as the Nine Hells of Baator or the Nine Hells, is a lawful evil-aligned plane of existence. It is one of a number of alignment-based Outer Planes that form part of the standard Forgotten Realms cosmology.

Baator is stylised as a plane of sinister evil and cruelty. The different types of devils that dwell here obey a strict hierarchical caste-like social structure. Each continually plots to advance their position through treachery and deception. Unlike the demons of the Abyss, the devils are highly organised, with a logical and calculating nature.

The plane itself is composed of nine different layers, each of which models a differing but no less inhospitable and dreadful environment, including barren plains of ash and rock to frozen wastes of endless ice.

Inhabitants
The principal inhabitants of Baator are the devils, fiendish creatures of pure lawful evil; the most populous variety of devils are the baatezu, a race which effectively rules the plane. The devils are in a constant conflict known as the Blood War with the chaotic evil demons. The ultimate rulers of Baator are the Lords of the Nine, also called archdevils or Archdukes; each one rules absolutely over one of the layers. The current political climate of Baator was determined by a civil war known as the Reckoning of Hell.

Besides the devils, Baator is home to evil deities such as Tiamat and Kurtulmak, as well as hell hounds, fire giants, rakshasas, and other evil creatures. A few mortals live in well-defended fortresses in Baator.

Baator is also populated by several types of petitioners, the most common being soul shells. These are ghost-like forms which can be molded by the devils into increasingly horrific and agonized forms; ultimately, their destruction results in their essence merging with that of Baator. Especially evil petitioners become lemures, mindless blobs of molten flesh who serve as shock troops in the Blood War and basic servants to other devils.

In earlier Planescape supplements, another type of creature, the nupperibo, is said to inhabit Baator as a remnant of an ancient race that existed long before the Baatezu. Nupperibos grow naturally from larvae present on the plane if left to develop. Since the arrival of the Baatezu, the larvae have been molded by the devils into lemures in an effort to prevent large numbers of nupperibo developing.

Structure
Baator is spatially infinite, consisting of nine infinite layers or sub-planes.

In the standard D&D cosmology, Baator’s first layer, Avernus, shares borders with the neighbouring planes of the Infernal Battlefield of Acheron and the Bleak Eternity of Gehenna; travel is possible between Baator and these planes at certain locations.

In the Forgotten Realms cosmology, Baator links via the Astral Plane, to Toril, the Prime Material Plane. A number of portals directly connect it with the Barrens of Doom and Despair, Clangor, and Blood Rift.

The layers of Baator are configured as a descending cone, with each layer successively lower than the one before it, as opposed to the Upper Planes of good alignment, where one goes higher to enter deeper into the plane.

Layers
Baator has nine layers:

Avernus
The first layer, Avernus, is a vast charred wasteland of rubble over which the iron towers of the Dukes of Hell stand. Legions of devils march across the plains in continual readiness for the next battle of the Blood War. A red light suffuses the sky and huge fireballs fly across the layer, randomly exploding wherever they hit.

The Bronze Citadel is a huge fortress city, housing massive numbers of devil troops and war machines. It is constantly being added to in the form of new fortifications against attacks. Lord Bel, a powerful pit fiend, is the current ruler of Avernus, having betrayed the former lord, Zariel, to obtain the position. He resides in a personal fortress at the center of the Bronze Citadel.

Tiamat, the five-headed deity of evil dragons, stands watch over the way to the next layer. Nearby exists the Pillar of Skulls, a hideous landmark of trophy-skulls of those killed in the Blood War that reaches a height of more than a mile close to the entrance to the second layer.

A number of godly realms exist on Avernus, including Draukari, realm of kobold deity Kurtulmak, goblin deity Bargrivyek's deceptively titled realm of The Peacable Lands, and Abthalom, the Nether Reaches, realm of dragon-queen goddess Takhisis.

Dis
The second layer, Dis, is a burning city of iron known as the Iron City of Dis. The walls of the buildings of the city radiate extreme heat, as do the stones of the streets; more than brief skin contact results in severe burns. The Archduke Dispater rules this layer from the Iron Tower, an impregnable fortress that reaches far into the sky and can be seen everywhere on Dis.

Minauros
The third layer of Minauros is an endless bog of vile pollution. The weather on Minauros consists of acidic rain and harsh winds.

The city of Minauros the Sinking is located here, so called because the weight of the city causes it to continually slip beneath the slimy waters; only the endless efforts of thousands of slaves prevents it from doing so. The kyton city of Jangling Hiter, City of Chains can also be found on this layer.

Mammon the Viscount is the ruler of Minauros, he resembles a long serpent with a human torso. He rules from the centre of the city, within a huge mausoleum like structure.

Aeaea, the secondary realm of the goddess Hecate is on Minauros.

Phlegethos
Phlegethos is a fiery wasteland filled with active volcanoes and rivers of molten lava. Lady Fierna and Archduke Belial are the lords of this layer. Few can exist here for long without suitable protection from the extreme heat. The city of Abriymoch is composed of hardened magma in the caldera of a volcano and is somewhat more bearable than the rest of Phlegethos. Fierna and Belial reside in a palace of pure obsidian high up on one side of the city.

Stygia
Stygia, the fifth layer is a freezing layer of cold and ice dominated by a murky ocean fed directly by the River Styx. The dark sky is constantly filled with lightning storms. Tantlin, the City of Ice, is built on a huge ice floe with a large harbor to the river Styx, and is ruled over by a huge pit fiend. The lack of any kind of law enforcement leads itself to gangs controlling much of the city. Prince Levistus rules over this layer, frozen in a giant iceberg floating in the harbor.

Godly realms on this layer include, Sheyruushk, realm of sahuagin deity Sekolah, and Ankhwugaht, realm of Set.

Malbolge
Malbolge is an endless mountain where rockslides and avalanches of boulders are common. Numerous copper fortresses provide some refuge from the avalanches. The Hag Countess rules from her mountain-sized boulder fortress, which perpetually rolls down the slopes of Malbolge.

Maladomini
Maladomini is a barren landscape scarred by countless forgotten ruins, abandoned mines and gruesome subterranean dungeons. The city of Malagard is the layer's primary settlement. Archduke Baalzebul presides over this layer.

Cania
Cania (or Caina) is an unimaginably cold wasteland, few living things can survive more than a few moments in an unsheltered area. Huge fast moving glaciers crash around the layer sending snow and ice up in the sky.

The layer is ruled over by Mephistopheles, from his great citadel of ice Mephistar. It sits upon a giant glacier called Nargus, the movement of which is controlled by Mephistopheles himself. Inside Mephistar huge heated baths and fire warm the citadel, providing quite a comfortable environment.

Nessus
Nessus is the ninth and deepest layer of Baator. It is of pits and ravines of virtually endless depths. The great city of Malsheem lies immediately below the layer between Cania and Nessus and is the largest city in all of the Outer Planes. Here, Asmodeus rules over the entire plane, and thus the entire race of devils.

Historical influences
The topography of Baator is broadly derived from the Hell described in Dante Alighieri's The Divine Comedy, although the arrangement and names of the layers of Baator differ greatly from the circles of Hell described by Dante. The Outer Plane of Mount Celestia is likewise loosely inspired by Dante's depiction of Heaven and Mount Purgatory.