Phlegethos
The fourth circle was the Hell that most resembled the stereotype of a fiery world of eternal damnation, filled with active volcanoes, rivers of liquid fire, molten rock, ash hills, smoking pits, unbearable heat, all wracked by tremors and earthquakes. Even the air seemed aflame and thus Phlegethos was considered to be fire-dominant. In the World Axis view, Phlegethos was a cavern several miles below Minauros, where burning lava poured out of fissures in the ceiling. The city of Abriymoch was the seat of power in this realm, built of hardened magma, obsidian, and crystal in the caldera of an extinct volcano which provided visitors some protection from the elemental environment found throughout the rest of the plane.
https://forgottenrealms.fandom.com/wiki/Nine_Hells
It was the most travelled of the Nine Hells, with hamatula guard patrols constantly hunting for intruders. Other common inhabitants, many of which stayed in the stinking fens on the outlands of the layer, included lemures, spinagons, imps, barbazus, abishai, and cornugons. There were also the less devilish efreeti and hell hounds as well as lawful evil fire elementals and mephits, the latter of which worked as spies for any who would reward them.
Abriymoch-
The seat of Fierna and Belial's power was the stronghold known as Abriymoch, the primary, if not only, city in Phlegethos. It was built in the caldera of the largest volcano in the realm, a hollowed out mount still overrun with molten rock. The buildings inside were constructed of jagged obsidian, igneous rock, dark glass, basalt and other crystals and the lips of the crater were crowned with towers. The fortress was composed of a series of chambers stacked on top of one another that opened into the volcano's hole through balcony-like structures and were connected to each other by stairs, shafts and a grand central spiral that snaked around the inner edges. Some rooms stretched throughout the inside of the volcano's sloping structure and had windows and other exits that opened to its outer walls, which were constantly poured over by lava rivers. The city's actual streets were so flooded with lava that foot travel was impossible, forcing visitors to pay for one of the dented, green-steel gondola manned by hundreds of spinagons and barbazus to ferry them to their destinations. Green-steel, in fact, was a primary export of Abriymoch, the valuable ore being derived from Phlegethos's magma which made it a primary weapons and armour trade centre in Hell. Relatedly, Abriymoch was the strongest citadel in the middle hells, with black towers that kept innumerable merregons and elite osyluths and malebranches. Hell hounds were also famous stays of Abriymoch, kept in kennels and raised in breeding pits that produced monsters to rival those defending Nessus. Technically, the city was ruled by the pit fiend Gazra, although he answered directly to the archdevils, from a crystalline castle housing a legion of 5,000 hamatula reserves. His forces, also comprised of bone devils, were responsible for hunting down deserters, capturing unauthorized souls that slipped past the upper layers, spotting corruption amongst officers and checking the paper work for mortals and devils alike. Many unwary souls were killed by the zealous guardsmen as well as the hellish environment conditions, so few came to Phlegethos by accident, although intruders weren't much better off, being imprisoned in the seemingly inescapable dungeons under Abriymoch. Abriymoch was also home to the Diabolical Courts, a maddening complex of loopholes and ancient precedents where various legal disputes between devils could be settled and souls condemned by an infernal contract could petition for their freedom. Ironically, despite being a place of unflinching law, matters of security and legalistic argumentation, Abriymoch was also a respite for many devils. Many of the laws governing Abriymoch allowed it to be run as a kind of carnal carnival, filled with infernal versions of taverns, theatres, casinos and various other establishments for the fulfilment of darker desires. Fierna's Palace-
A key example of Phlegethos's pleasurable aspects was Fierna's palace, a slender, serpentine tower of crystal outside of the city, wreathed in blue flame and surrounded by a ring of magma pools. Only she and her closest companions were allowed inside since Belial spent a majority of her time there. Exorbitant marble halls and a bejewelled décor could be found deep within the tower, and following a scorching staircase underground, were deep caverns known as Fierna's pleasure domes, each dedicated to a different vice. The floor had grates that allowed access to the prison cells below, many of which housed celestials and paladins for a bored Fierna to prod with a long lance at her leisure. A fair fraction of the captives were Fierna's ex-lovers, allowing her current suitors to see the fate of those before them which they rarely considered they could one day share. https://forgottenrealms.fandom.com/wiki/Fierna
The seat of Fierna and Belial's power was the stronghold known as Abriymoch, the primary, if not only, city in Phlegethos. It was built in the caldera of the largest volcano in the realm, a hollowed out mount still overrun with molten rock. The buildings inside were constructed of jagged obsidian, igneous rock, dark glass, basalt and other crystals and the lips of the crater were crowned with towers. The fortress was composed of a series of chambers stacked on top of one another that opened into the volcano's hole through balcony-like structures and were connected to each other by stairs, shafts and a grand central spiral that snaked around the inner edges. Some rooms stretched throughout the inside of the volcano's sloping structure and had windows and other exits that opened to its outer walls, which were constantly poured over by lava rivers. The city's actual streets were so flooded with lava that foot travel was impossible, forcing visitors to pay for one of the dented, green-steel gondola manned by hundreds of spinagons and barbazus to ferry them to their destinations. Green-steel, in fact, was a primary export of Abriymoch, the valuable ore being derived from Phlegethos's magma which made it a primary weapons and armour trade centre in Hell. Relatedly, Abriymoch was the strongest citadel in the middle hells, with black towers that kept innumerable merregons and elite osyluths and malebranches. Hell hounds were also famous stays of Abriymoch, kept in kennels and raised in breeding pits that produced monsters to rival those defending Nessus. Technically, the city was ruled by the pit fiend Gazra, although he answered directly to the archdevils, from a crystalline castle housing a legion of 5,000 hamatula reserves. His forces, also comprised of bone devils, were responsible for hunting down deserters, capturing unauthorized souls that slipped past the upper layers, spotting corruption amongst officers and checking the paper work for mortals and devils alike. Many unwary souls were killed by the zealous guardsmen as well as the hellish environment conditions, so few came to Phlegethos by accident, although intruders weren't much better off, being imprisoned in the seemingly inescapable dungeons under Abriymoch. Abriymoch was also home to the Diabolical Courts, a maddening complex of loopholes and ancient precedents where various legal disputes between devils could be settled and souls condemned by an infernal contract could petition for their freedom. Ironically, despite being a place of unflinching law, matters of security and legalistic argumentation, Abriymoch was also a respite for many devils. Many of the laws governing Abriymoch allowed it to be run as a kind of carnal carnival, filled with infernal versions of taverns, theatres, casinos and various other establishments for the fulfilment of darker desires. Fierna's Palace-
A key example of Phlegethos's pleasurable aspects was Fierna's palace, a slender, serpentine tower of crystal outside of the city, wreathed in blue flame and surrounded by a ring of magma pools. Only she and her closest companions were allowed inside since Belial spent a majority of her time there. Exorbitant marble halls and a bejewelled décor could be found deep within the tower, and following a scorching staircase underground, were deep caverns known as Fierna's pleasure domes, each dedicated to a different vice. The floor had grates that allowed access to the prison cells below, many of which housed celestials and paladins for a bored Fierna to prod with a long lance at her leisure. A fair fraction of the captives were Fierna's ex-lovers, allowing her current suitors to see the fate of those before them which they rarely considered they could one day share. https://forgottenrealms.fandom.com/wiki/Fierna
Geography
Fierna ruled the fiery layer of Phlegethos, the most archetypal of the Hells that commonly appeared in mortal minds when hell was mentioned. Like the Plane of Fire, the unending flames and unbearable heat swiftly scorched most forms of life, with much of the scalding expanse being covered in ashen hills and smoking plains. Of the lawful planes of Hell, Phlegethos was the most environmentally chaotic; tremors were common and violent eruptions or the random openings of fissures were sporadic, although despite making it more dangerous it gave trespassers a wider choice of hiding spots.
The tortured hellscape was rife with mountainous volcanoes which spewed the rivers of molten magma that dominated the plane, the structures of Phlegethos having to be made to withstand its random redirects. All bodies of the liquid lava were interconnected, either in bubbling pools, lakes of fire, or igneous seas. The firefalls, where the fiery streams fell from sharp ridges, made it one of the most visited hells, at least by magic-wielding outsiders that sought to use the flames in works of incredibly alchemy or magical item forging.
Supposedly, Asmodeus killed the original divine master of Phlegethos, his grave being a foundation for some crucial part of the plane. Regardless of how it was then, Phlegethos was currently a place of pain, with fires that seemed to harbour a strange, merciless sentience. Though welcome denizens, even those not immune to fire, seemed unharmed by them, intruders found that the flames leapt through the air, unnaturally bending to gleefully ignite them and their possessions. Even without the jumping flames illuminating the starless void above, simply staying still in Phlegethos was likely to get one destroyed, if not by the pyroclastic pumice interspersed throughout the flesh-roasting air then by one of the roaming inhabitants.
Alternative Name(s)
The Fourth Layer
Type
Dimensional plane
Location under
Owner/Ruler
Ruling/Owning Rank
Contested By
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