The Pit is the collective name given to a number of the Outer Planes of Existence by its inhabitants, although the majority of other beings know it as "The Demonic Planes". In Hachiman is is known as the "Nether Regions".
The Multitude of PlanesEdit
The Palace of AgonyEdit
At the very heart of the Pit is the Palace of Agony, an incomprehensibly gargantuan structure fashioned using paradoxical geometry that could not possibly exist anywhere else. The Palace serves as more than just the seat of the Snake and Night Demons, as within its vast walls are the Hellhound Kennels, Nightmare Stables and dining halls of seemingly infinite size, where the ghastly inhabitants gather to feast on dead and very-much-alive foodstuffs in banquets of unmatched horror and depravity.
It is from the Palace of Agony that the Wild Hunt sets off, and it is to the wastes and pools upon which the Palace is built that the essence of a defeated Demon returns, to await their rebirth in a new body. Only the most powerful or most important of Demons partially escape this fate, namely those belonging to the highest tier - Sith, Ishtra, Kalin, Shakor and their fellows, and others of equal rank.
Being at the centre of the Demonic Planes, insofar as multiple dimensions occupying the same space can have a location, the Palace of Agony is easily accessible from all the other Planes, although it is admittedly far easier to get in than it is to get out. However, attempting direct access from the Earthly Plane is incredibly unwise, since the most potent of dimensional barriers guard this Plane.
The Plane of BileEdit
A particularly repugnant Plane which is occupied by many of the foulest of Demons, such as Plague Demons and Muck Demons among others. Although relatively unstable compared to others, the Plane of Bile is still the site of the Palace of Shakor, at present conveniently situated "close" to his master Ishtra.
It is from the Planes of Ichor and of Obsidian that the Plane of Bile can be most easily accessed, though it is also partially bordered by the Elemental Planes of Fire and of Water.
The Plane of BloodEdit
For many of the inhabitants of the Pit, this is one of the most delightful of Planes, an entire dimension of blood and other vital fluids that combine to make a truly revolting place for any other entity. It is also the site of the Palace of Relem, despite its near-total liquid nature, for as with all the Demonic Planes, the normal laws of nature simply do not apply.
It is from the Planes of Ichor and of Steel that the Plane of Blood can be most easily accessed, though it is also partially bordered by the Elemental Planes of Earth and of Fire.
The Plane of IchorEdit
As any High Priest or senior demonologist will know, the mystical substance of ichor flows through the veins or is a portion of the form of all supernatural beings, the exact amount causing differences in the power of the given entity - from Demonspawn to god, all possess ichor. Consequently, many of the mightiest Demons choose to dwell here, and it is also the site of the Palace of Ishtra.
The Plane of ObsidianEdit
The Plane of Obsidian is particularly prone to what a Human would call natural disasters, namely earthquakes and volcanoes, since it is perhaps the most unstable of all the mainly solid Planes. This is due to the fact that it is closely attuned to the Elemental Plane of Fire, which acts to destabilise it. It is also the site of the Palace of Kalin.
It is from the Planes of Bile and of Platinum that the Plane of Obsidian can be most easily accessed, though it is considerably easier to do so from the Elemental Plane of Fire.
The Plane of PlatinumEdit
This Plane is something of an unusual one among the major Outer Planes, given that it lacks many of the features that are seen as attractive to Demonkind, such as destructive power, foulness or decay, but nonetheless is the preferred home of many powerful Demons, such as Iron Demons and Lightning Demons. It is also the site of the Palace of Vradna and of his legion of Gargoyles.
It is from the Planes of Obsidian and of Rust that the Plane of Platinum can be most easily accessed, though it is also partially bordered by the Elemental Planes of Air and of Earth.
The Plane of RustEdit
A favourite among many high-level Demons, not least of which are the Rust Demons which dwell on this Plane almost to the exclusion of all others, the Plane of Rust is also the site of the Palace of Myurr, interestingly situated near to his diametric opposite among Demons - the terrible Sith.
It is from the Planes of Platinum and of Steel that the Plane of Rust can be most easily accessed, though it is also partially bordered by the Elemental Planes of Air and of Earth.
The Plane of SteelEdit
In all dimensions, steel is prized for its strength and ability to destroy if correctly manipulated, and it is here that the greatest weapons of the Demons are forged, before they are imbued with the appropriate spells to make them unique to their wielders. It is also the site of the Palace of Sith, a bizarre construct built from snake scales and perched on the very edge of a bottomless chasm - it too uses the insane geometry of the Palace of Agony, which can drive a person mad simply by looking at it.
It is from the Planes of Blood and of Rust that the Plane of Steel can be most easily accessed, though it is considerably easier to do so from the Elemental Plane of Earth.
The seven major Outer Planes, together with the Palace of Agony, are of course not the only dimensions that are under the control of Demonkind, or at least influenced by them. Chief among these lesser ones are the home Planes of the Death Spider and Mirror Demon, though certain parts of the Spirit Plane also number among them, specifically those inhabited by Nanka or Spirit Demons.
The Abyss was also part of the Demonic Planes at one time, but appeared to lack any significant Demonic presence by the time Bythos took over. The continued presence of Anemorus and Ectovults suggests that this exodus was limited only to full Demons, rather than the indigenous inhabitants.