Nine Hells

The Nine Hells of Baator, more commonly known as simply the Nine Hells, is the home plane of the devils. It is a plane of evil and, unlike the Abyss, is highly organized with a strict caste system.

Layers
There are very few portals that will lead to the hells. To travel to one layer a person usually had to traverse through the other layers, starting at the first layer, Avernus.

Avernus

 * &rarr; Main article: Avernus.

Avernus is the first layer of the Nine Hells, and the arrival point for most visitors to the Hells. Avernus is a rocky wasteland with rivers of blood and clouds of biting flies. The Archduchess who rules over Avernus is the fallen angel Zariel. Her advisor, a pit fiend named Bel, was replaced by Zariel after Bel fell out of favor with Asmodeus. Zariel's soaring keep is a basalt citadel, and her once-beautiful skin and wings have been ruined by the fires of her own evil alignment.

Tiamat is a prisoner on this layer of the Nine Hells, confined to her domain by an ancient contract with the Lord of the Hells. Arkhan the Cruel has a keep on Avernus near his deity's prison. After the defeat of Vecna in Vasselheim, Arkhan took his newly-acquired Hand of Vecna and Teleported back to his keep in Avernus. As of Campaign 2, he is still trying to unlock the Hand's power in order to free the Scaled Tyrant and unleash the Dragon Queen upon the other planes of existence.

Dis

 * &rarr; Main article: Dis.

Dis is the second layer of the Nine Hells. It is a labyrinth of canyons, sheer mountains that are filled with iron ore. There are iron roads that span through the canyons with bridges that lead over giant crevasses and dark landscapes. The Iron City of Dis is located on this layer. The archdevil who rules over this layer is Dispater, who styles himself the "Iron Duke". Dispater never leaves his Iron Tower unless directly commanded by Asmodeus. When he does so, he always has at least nine different backup plans and escape routes prepared.

Nessus
Asmodeus, Lord of the Hells, rules from his fortress, Malsheem, on this deepest layer of the Hells.

Trivia

 * Avernus has yet to appear in either campaign of Critical Role, beyond Joe Manganiello's information about Arkhan. This article assumes that the canon Dungeons & Dragons description of Avernus is the same as the one in Critical Role's multiverse.
 * The Blood War between devils and demons has been confirmed as canon in the Nine Hells of the Critical Role multiverse, both by an untrustworthy glabrezu using the alias "Juurezel" and by the tapestries found on the walls of the Circlebound Chamber within the Heirloom Sphere.