What is "baator"

In the Dungeons & Dragons fantasy role-playing game, 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 Dungeons & Dragons (D&D) cosmology, used in the Planescape, Greyhawk, and some editions of the Forgotten Realms campaign settings. It also exists as one of a number of faith-based Outer Planes that form part of the separate 3rd-Edition Forgotten Realms cosmology, used in the setting of the same name.

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 organized, 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.