Sealed Realm

The Sealed Realm, also called the Abyss and Absens Aeternatus by the Eidolons, is a pocket dimension within the main world, created by the Seven Goddesses as a means to imprison and punish the Eidolons after the Last Immortal War. It consists of a small and unusually shaped island, inhabited only by the Eidolons at first, and then later by the souls of deceased Mortals, and eventually by the Sin Eaters as well. It is a bleak and goddessless place where the land is eternally cloaked in twilight, and the atmosphere is choked by the realm's natural voidal miasma. The elements of the Goddesses do not flow here, and thus magic is exponentially less potent than in the overworld. The inhabitants of the Sealed Realm eventually learned to control the element of the abyss, known as Void, or Voidal magic — this is a specific lack of elemancy, a sort of anti-magic energy.

Locations
These are the current locations as of the Current Era.

Caelus Region
Old Asa (formerly called Asa) - the former city of the Arkangels, now left to ruins after being overrun by Sin Eaters. An incredibly dangerous location, not just because of the structural decay, but because of the numerous Sin Eaters who now roam within its borders.

Ius Lake - a small body of water that hosts unique plant life and was originally used as the entry point for Mortal souls of the deceased, at which time it was commonly called the Spring of Rebirth. One of the few locations that Sin Eaters tend to stay away from.

Forgotten Atria (formerly the Immortalis Atria) - a governmental building that used to be a gathering place for the Angelic Court and the Daemonic Hierarchy, now left in ruins after being overrun by Sin Eaters early on. A large number of documents were lost or destroyed as a result of this, and most attempts to recover them have failed.

Sinner's Spire - an unusually thin platform of rock just off the western coast of the Caelus Region, close to the Forgotten Atria. The Angelic Court used to bring Arkangels here to deliver their punishments when laws and rules were broken.

Furvus Region
The Sanctum (formerly the city of Furvus) - originally the city of the Daemons, at which point it was called Furvus. When the displaced Arkangels from Asa arrived seeking refuge, the city was renamed to The Sanctum, and the surrounding region was given the name of Furvus instead. Now the sole settlement in The Abyss, and the main safe spot, though it is now often targeted by Sin Eaters. The Angelic Court and Daemon Hierarchy joined together here to form the Immortalis Coalition, a unified governing body that seeks to find a way to escape The Abyss for both Daemons and Arkangels. It is currently headed by Mephisto Pheles and Lucifer, with Eidolons such as Judas and Asmodai, all from the sealed seven, who escaped their tomes and entered the Sealed Realm from the overworld to help free the trapped Eidolons. As an extension of this coalition, they have also established contacts with Mortals in the overworld, through the Cult of Pheles. Currently, members of the sealed seven are the only Eidolons who can freely travel between the Sealed Realm and the overworld.

The Donarium - a newly constructed building which serves as a guard tower to keep watch for incoming Sin Eater attacks. Watch shifts are swapped each week and are headed by a group of five to ten.

Letum Hill - previously an unremarkable location, it is now the location of the Seal Fissure, a break in the seal on The Abyss, which allows those with ties to the overworld to leave and re-enter the Sealed Realm at will. It's functionality is limited in this way due to the weakness of the fissure, though if the fissure were to expand enough, it may allow the remaining Eidolons to freely leave the The Abyss. This is the current goal of the Immortalis Coalition, and the hidden agenda of the Cult of Pheles, though the cult does not know what their actions are really doing, as they act only in search of the power that Mephisto Pheles can give them.

Other Locations
Swamp of Mirth - a swamp that serves as a neutral connecting region between the Furvus and Caelus regions. It is inhospitable and treacherous to cross, and initially stopped the Sin Eaters from coming into the Furvus Region, but it seems as though they have taken to crossing the Inner Somnus Sea now instead.

Somnus Inner Sea - a small inland sea, bordering both the Furvus and Caelus regions, as well as the Broken Isles. It is an eternally still body of water, and none know what lays beneath its inky surface, though few would dare to explore it.

The Broken Isles - an expansive series of small islands that borders the Inner Somnus Sea from the Ocean of Eternity that surrounds the small continent. There is not much of note here.