While the physical multiverse itself is massive, its really the tip of the iceberg. Formed after the first great experiment that produced the nE- the Afterworld was created to house everything that does exist, has existed, will exist, and even that which might have existed. Innumerable worlds exist side by side, linked only by the  Afterworld. And the Afterworld is linked through itself by the gossamer strands of imagination. if you believe it exists, you can find it. That's the core of the problem.
In order to prevent problems and paradoxes from arising in the Afterlife, all lands and realms are isolated from each other. Only someone who has "been there" has repeated access to that world, although portals between extremely close worlds do exist. Items too, that have been in one world can be used to bridge the gap between worlds. Once a being makes contact with this new world they can travel freely between them. By being set up this way, it allows for reasonable travel between planes of existence. This also served as a buffer against mass transit from realm to realm. with mass transit comes the possibility of raiding parties. Even at the beginning of the Afterlife, this was a cause for much alarm.
   From the beginning not much has changed, there are three levels to the Afterworld. The primary world- Midworld is the first and most common area of the Afterworld. While it doesn't have the largest levels, it does have the largest number of souls. (Souls being what you get when you take all physical properties away from life energy.) This level is  also considered the most social of levels. It's at the center of this the Nexus was formed. It's there that every soul that comes into the afterworld is processed and assigned. The white lady has the job of not only protecting the Nexus, but sorting all the souls that come through into areas where they are compatible. And in cases where they would cause too much damage to be assigned a realm, they are offered the opportunity to be isolated or returned to the physical world. In rare cases these souls make it through to other areas of the afterworld.
The second area is the dungeons of the Afterworld. It's known by many names hell, hel, and even names other than hell. this was originally considered a separate segment of the afterworld, and had 1000 demons for every soul the Afterworld holds, will hold, and already has, raising the question of "has everything already happened yet?" This balancing act was shattered by the nE who took hell from a closed system to opening it to the mid level of the afterworld and even opening passages to the upper level of the
Afterworld known as the Ascendant. This was received with a great deal of horror from cities and whole countries who discovered they were open to demonic attack and had few weapons to resist them. Into the midst of this chaos the nE returned, and refusing to undo the problem, they created another. Using powers known only to them, They remade the Nexus and gave it the power to select a champion. A guardian to protect the white lady and further the cause of the Nexus. this worked far far better than planed.
        The champion, known as a ghostrunner was sent forth to repel not only demonic attacks, but also to bring down any threat to the Nexus. To that end the first ghost runner went out and laid waste to anything that he perceived as a threat. Even to the extent of challenging the illuminati, the beings inhabiting the upper level of the Afterworld. Some of the illuminati spent eons purifying their spirit and their realms only to have the ghostrunner brutally smash their realms to bits. In anger they forged a vengeful curse. Any ghost runner that was chosen would be killed. The nE altered the next ghostrunner so that only the white lady could kill him. the illuminati responded by cursing the white lady so she would be forced to kill him. The nE then responded by making sure the Nexus would only chose the most capable white lady. Giving up in disgust, the illuminati created the guardians to put an end to the demonic attacks, assuming that with them gone, the Nexus wouldn't need a ghostrunner.
While it was a comendible theory, the reality of it was that the attacks continued, and even in the face of the afterlife's angelic protection, the demons grew and fought and became bigger until they learned to access thier realms for protective power. They discovered if they linked demons into thier realm's core, they gained even more power. The more demons these "demon lords" aquired, the more powerful they became. It was when besh yialda found you got a lot more power by plugging a soul in instead of a demon that truely massive attacks on the Nexus began. by this time fifteen white ladies had come and gone. the ghostrunner of the time, known as Doys, savaged the demon lords severely. He was also smart enough to know that he was only going to be running around in circles unless he could organize the demons into regulating themselves, forcing them to pull back and create a council of thier own. With self regulations the first scraps of the dark council was formed.
Doys never lived to see his plan for fruition, but the council in self interest regulated the attacks so that no demon lord would rise in power above the others. For eons this struggle back and forth continued between parts of the Afterworld, until Eliziabeth, the latest white lady set her sights on ending the struggle once and for all. To that extent she researched the nE and all thier weapons, but it was pure fortune that dropped Ial into her lap. Utilizing a former weapon of the nE against the enemies of the Nexus, the white lady is making a play for the whole Afterlife, and maybe even the end of the nE themselves...