Heirir

Heirir is the underworld of the Emdes universe, and is ruled by a council of archdemons and the archangel Aesturex. Heirir itself serves as the underworld to the whole physical universe, as well as some other planes of existence, and is as such extremely large, however, there is also heaven, to which some souls pass on to. The main difference of Heirir to the other planes is that demonic essence flows through it, which is extracted from freshly dead souls in the purgatory and, over centuries of exposure, turns Heirir's denizens into demons.

Structure
Heirir, while usually referred to as a singular plane, is actually a clusterplane consisting of multiple, smaller planes that are very closely linked with each other, to the degree that, in some cases, permanent gates and transitions have established themselves. These planes are reffered to as floors or levels with either a number behind them and or a specific name, should they have an especially remarkable feature. The deeper into Heirir one goes, the higher the associated number of the level will be.

Creatures from seperate worlds are usually kept seperate even in the afterlife, at least until they have reached a certain age and degree of demonification, upon which they will be able to enter levels where creatures from different worlds are allowed to mingle. Of course, should two worlds have interacted excessively outside of the afterlife already, the requirements for their mingling will be lowered accordingly. This barrier is in place as to protect the new arrivals which might have problems (both physically and mentally) dealing with the wide variety of different beings in the underworld - after all, not everybody wants to spend eternity amongst a mix of creatures that could include anything from aliens to dragons to shadowy amalgamations.