Carceri
The Tarterian Depths of
This ain't a prison my friend, it's the prison.
Geography
The model for all other prisons in existence, Carceri is a plane of desolation and despair. Its six layers hold vast bogs, fetid jungles, windswept deserts, jagged mountains, frigid oceans, and black ice. All form a miserable home for the traitors and backstabbers that are trapped on this prison plane.
History
Living or dead, the locals are all bitter, plot revenge, and seem constitutionally incapable of telling the entire truth. Lost souls often take the form of maggots. The people of Carceri form communities of primitive savagery, in contrast to the "noble savages" of the The Beastlands
The most notable inhabitant is Zehir , God of Darkness and Poison. Though not in Carceri by choice, Zehir makes the best of his situation. He is not the ruler of this plane, rather he is by far the most dangerous inhabitant of what is effectively an inter-dimensional prison, and lords over those weaker or less cunning than him as a tyrant and a bully, using coercion, blackmail, and force to get what he wants.