Gehenna is a small demiplane in the far northwest of the demonic plane of Stygia. The remains of an ancient battlefield, Gehenna lies in a state of ruin as the conflict destroyed nearly everything of value. It mostly consists of wild lands and ruins and is divided by the frozen River Malebolge. Forgotten Words contains a vault of hidden demonic lore and is one of the few remaining landmarks in Gehenna.
While Gehenna is rarely a destination in its own right, it is one of the most common entry points to Stygia from Laurentia via a portal on King's Island. Pathways on the edges of Gehenna link it to The Death Cascade, Tartarus and Sanguinis Diabolus.
"Gehenna" is sometimes used as a colloquial term by older souls to refer to the plane of Stygia itself, as some past forms of Stygia took this name instead.