OK, huge pesky laundry-list of questions for you, Ed!
What will the goals/numbers of the denizens there be? Are they mostly powerful souls who resisted the Thread's attempts to reabsorb them, or more like an alien species that are native to the plane? Is it a fully realized extra-dimension with its own cosmos and worlds, or more like a bubble/pocket dimension parallel along the Threaded Path? What happens to a soul when the fiends steal it along the path? Eaten or twisted into members of the dark army?
Do the Pits of Endless Strife tie into the magical effects of necromancy's soul displacement? I could see perhaps a soul being taken from a wizard and being traded for an immortal dark energy equivalent to sustain their consciousness into lichdom. Since their "soul" was already taken away from the path, they wouldn't fear being reabsorbed after a natural death. Do undead animation effects tap into this sort of dark energy, or is that from a separate plane of existence altogether? (I know we don't have "shadow" anymore, is it the "Lumbral" now?)
