The Ten Hells (Sometimes called Baator) are a group of linked demiplanes that contain a variety of landscapes and climates. The native species of The Ten Hells are Devils.
History
The Hells were created over time by Asmodeus, starting with one layer, and slowly building up to the 10 layers that exist.
The layers of Stygia and Cania were on the list of "possible convergence planes", noted for having the possibility of cross contamination with eldritch powers of the Underdark Old Ones.
Layers
Stygia
Stygia is the fifth level.
Malebolge
Archdevil
Glasya was the biological daughter of Asmodeus, and served as the ruler of Malebolge until her promotion to ruler of Nessus. Callum was a barbed devil who served Glasya in her time as Malebolge's ruler.
Cania
Cania is the eigth level.
Nessus
Nessus (also called Bolgia) is characterized by flaming landscapes and rivers of lava emerging from limitless plains of volcanoes. Jagged rocky peaks and steep drops into molten lakes provided a treacherous terrain for any creature without the ability to fly. For this reason, almost every resident of Nessus could fly safely around the flaming land.
Archdevil
Asmodeus himself was the ruler of Nessus until the addition of the tenth layer, Hellmar. The Archdevil of Nessus sits on a throne in the middle of a towering, raging, fireball known as Malsheem. Malsheem contained millions of souls reaped from the Material plane in a labyrinth of chasms and peaks guarded by Asmodeus' best armies.
Pathway to Hellmar
One gateway to Hellmar existed in the center of Malsheem. Guarding the gateway was the three headed dog known as Cerberus. The gateway itself required travelers to face their own fears, and was inscribed with the following poetry:
"To get below you'll show your worth. For if you want to see the earth Your darkest fears you must command do not run, you have to stand a chance to win and fears aswayed you'll soon Descend and go on your way."
Notable Locations
Hellmar
The original iteration of Quelmar, given to the gods to Asmodeus per a loophole in the Pact Primeval. Though the gods had all but given up on Quelmar after Asmodeus took his claim, private consort with surviving members of the realm convinced the gods to "reboot" the Material Plane, allowing Asmodeus to continue his rule over the original.
New Citadel
Asmodeus, after leaving Nessus to rule Hellmar, built a massive citadel of magma and steel for his new seat as archdevil over the realm. The citadel was built alongside a new type of devil known as an Air Siren, who sing a horrid song so unholy that the air in the chamber itself flees, creating an unbreathable vacuum in whatever room the siren sings in.
