Phlegethos

Phlegethos, the fourth layer, is a fiery landscape whose seas of molten magma brew hurricanes of hot wind, choking smoke, and pyroclastic ash. Within the fire-filled caldera of Phlegethos’s largest volcano rises Abriymoch, a fortress city cast of obsidian and dark glass. With rivers of molten lava pouring down its outer walls, the city resembles the sculpted centrepiece of a gigantic, hellish fountain.
Abriymoch is the seat of power for the two archdevils who rule Phlegethos in tandem: Archduke Belial and Archduchess Fierna, Belial’s daughter. Belial is a handsome, powerfully built devil who exudes civility, even as his words carry an undercurrent of threat. His daughter is a statuesque devil whose beauty encases the blackest heart in the Nine Hells. The alliance of Belial and Fierna is unbreakable, for both are aware that their mutual survival hinges on it. (https://www.dndbeyond.com/sources/dmg/creating-a-multiverse#OtherPlanes)

Alternative Name(s)

Fourth Layer

Type

Dimensional plane

Location under

The Nine Hells

Owner/Ruler

Fierna

Additional Rulers/Owners

• Belial

Ruling/Owning Rank

Archdevil

Characters in Location

• Belial
• Fierna