Gehenna (Dungeons & Dragons)
In the Dungeons and Dragons fantasy role-playing game, Gehenna (in the current edition of the game, the Bleak Eternity of Gehenna; also, The Fourfold Furnaces or The Fires of Perdition), is a plane of existence of neutral evil/lawful evil alignment. 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 borders the Gray Waste of Hades and the Nine Hells of Baator.
The plane known as Gehenna was mentioned for the first time by name in the article "Planes: The Concepts of Spatial, Temporal and Physical Relationships in D&D", in The Dragon #8, released July 1977. The plane was mentioned again in an appendix of the known planes of existence in the original (1st edition) AD&D Players Handbook, published in June 1978, where it was described as "The furnaces of Gehenna of lawful evil neutrals".
The yugoloths call Gehenna home, and are its primary natives, though they originally hail from the Gray Waste - they dominate both planes, but in Gehenna their rule is more overt and in the Waste more subtle. The Tower of the Arcanaloths is also found on Gehenna. The leader of their race, known only as the General of Gehenna, moves his Crawling City from layer to layer according to his will. The City moves on thousands of fireproof legs and may climb the face of any cliff.
Gehenna consists of four planar layers; each layer consists of a pair of huge volcanos floating in space, joined at the bottom to form massive "earthbergs", hundreds of thousands of miles tall. Smaller mountain-shaped and -sized chunks of earth also float through Gehenna, occasionally colliding with the primary earthbergs. The first layer, Khalas, is a hot and fiery place, but the volcanos gradually grow colder as one passes through the layers; the third layer, Mungoth, is a cool place, while the fourth, Krangath, is icy and dead.
Khalas is the location of a number of godly realms, including the kobold deity Gaknulak's realm of Aknuthrak, the wererat god Squerrik's realm of Cheisin, Math Mathonwy's realm of Corriegrave, and Sung Chiang's realm of Teardrop Palace.
Chamada is the location of a number of godly realms, including the giant deity Memnor's realm of Thraotor and Sargonnas' realm of Palace of Deception. It also contains the realms of dead gods Iyachtu Xvim (Bastion of Hate), and Maanzecorian (Rictus). The town of Nimicri can also be found floating above the second layer.
In other cosmologies
- Cook, Monte: The Planewalker's Handbook, p. 21, TSR 2620
- Larme, John (November 3, 2000). Dangerous Games? Censorship and "Child Protection"  (PDF ). Queensland.
- Gygax, Gary (July 1977). "Planes: The Concepts of Spatial, Temporal and Physical Relationships in D&D". The Dragon #8 (TSR) I (8): 4.
- Gygax, Gary (1978). Players Handbook. TSR. ISBN 0-935696-01-6.
- McComb, Colin and Cook, Monte: War Games, p.46 (in: Hellbound: The Blood War, TSR 2621)
- UO-Planescape: Gehenna (Italian) page from Planescape Italian fansite