Gehenna, Also Known as the 13 Hells, is the land of Devils, and said to be ruled by Lucifer Himself. Gehenna is one of the 3 Realms in the Underworld, accessible through the River Styx upon departing the City of Penumbra in Limbo. Each Layer is ruled by one of 13 Archdevils.
It was once believed that Limbo was the first Layer of Gehenna, but it has since been disproven.
First Layer- Avernus - Bel
Second Layer- Lust - Fierna
Third Layer- Gluttony - Leviathan
Fourth Layer- Greed - Mammon
Fifth Layer- Wrath - Zariel
Sixth Layer- Sloth - Belphegor
Seventh Layer- City of Dis - Dispater
Eighth Layer- Heresy - Mephistopheles
Nineth Layer- Violence - Bael
Tenth Layer - Phlegethos - Belial
Eleventh Layer - Fraud - Beelzebub
Twelfth Layer - Treachery - Glasya
Thirteenth Layer - Pride - Lucifer