Hades

Few places in the multiverse inspire such terror and intrigue as the Plane of Hades wherein all the domains of hell are stoked by eternal flame. Whereas Elysium is mostly inhabited by very few but very powerful beings, Hades is overflowing with interlopers and mortals. Hades is a realm that is easy to reach (in every imaginable sense) but difficult to leave, making a direct journey there quite unwise. There is a great deal more to this Plane than the fire and brimstone which populates scripture and religious belief, it is afterall a hell for all beings (mortals and outsiders alike) and its subdomains are as far reaching as the damning of specific sin to small pocket dimensions designed to torture a particular individual in the most gruesome of ways. Hades has no specific overseer or ruler but its landscape is divided among those beings who wield the infernal power to take what they can by force. These beings are referred to in the material world as The Lords Who Lie Below, the distinction of that name implying that it is not just demons and devils who can claim the hellfires as their kingdom. The Lords Who Lie Below toil to gather as much power as they can and thus Hades is a Plane that is absorbed in eternal conflict, which is the greatest boon the material world could hope for because if all the powers of hell were united at last there is little doubt that all the other Planes would be ravaged. Because of Hades’ position in respect to the other Planes divine magic does not filter to it, meaning that mortals cannot rely on the powers of the Endless or the mercies of the angels to aid them if they choose to enter the hellfires.
Like Elysium, the Plane of Hades is large and divided into subdomains, but in addition it contains very specific and isolated dimensions, some of the most well know are thus:
The Hellfires -- Sometimes called the Nine Circles, the Hellfires are a tower of dimensions where the wicked receive their judgment for the atrocities and crimes they committed in life. The tortures that the damned receive in the Hellfires is too gruesome an affair to describe in text. They are often specifically designed to cause torment and suffering for the individual and are administered by devils. Each of the nine dimensions that make up the hellfires correspond to a particular judgement with the deepest level belonging to the treacherous who are imprisoned in ice. While one can only speculate the reasons why, all who reside in the Hellfires are not there to suffer. There are instances where a soul may reach the Nine Circles and feel no pain from its flames nor draw the ire of its devils, they can move between the circuits at their leisure and are given passage to speak with the damned.
Abaddon -- The black city of Abaddon is a meeting point for outsiders and interlopers. It exists of its own accord, floating above a burning lake of fire by its lonesome. While it does not have the majesty of the City of Brass, Abaddon serves a similar purpose. Mortals and outsiders who desire to bargain with the Lords Who Lie Below are received in Abaddon as it is also known as the City of Contracts. For this reason Abaddon is the only piece of “neutral” territory that exists in the Plane of Hades but by no means does that make it safer to travel, just that the dangers of the Plane will deal out their malice and murder in secret.
Ravenloft -- This mysterious dimension is watched over by a group of entities that, for lack of a true name are referred to as the Dark Powers. Ravenloft is a specific hell designed to be the torment of a handful of individuals. These men and women are referred to within Ravenloft as the Dark Lords but they are only immortal pawns whose suffering pleases the Dark Powers. No one knows where the Dark Powers originate from though some speculate that they are a very specific sibling of the Endless. No one knows why or how the Dark Powers allow divine magic to exist within Ravenloft (to be clear, divine power works there but it is not the Endless or the Angels who provide it). Only one Dark Lord is known to have ever successfully escaped Ravenloft and only because the Dark Powers could find no further way to torture them and grew bored with their presence. The Dark Powers are known to offer great boons to those who commit evil acts within Ravenloft or who appease them in any way, but these temptations are only dealt out to expedite a gruesome and usually ironic end for their champions.
The Abyss -- For those whose works in life merit a punishment but not torture there exists a cleft in the Plane of Hades overlooking a yawning abyss. Upon that cliff these souls are chained and left, not to suffer but merely to reside in purgatory never to know pain or bliss again. The abyss itself is the catchall hell for many of the denizens of the multiverse, for there are beings who are too abstract in physiology or psychology to understand the primitive forms of torture and pain that mortals endure, thus these abominations are hurled into the abyss which has no bottom and from which there is no possible returning from.