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. The Old 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 Kings 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.