Chaosmancer
Legend
Funny use of the term "dimension".
You cannot walk, take a boat, or fly to The Abyss. It is not on the same plane of existence. I am not sure how you can call it the same dimension.
Well, I'm not sure the exact right term to use here. It isn't like Forgotten Realms, Greyhawk, Eberron, Mystara, Darksun ect use the same exact cosmology.
If you want me to say "from outside this crystal sphere of influence but not one of the planes of existence we are typically familair with which may also lay outside of that crystal sphere" I can. But I think my point was understood.
That and the whole NE Yugoloth as uncaring evil and nihilistic creatures fit wells with the idea of unfathomable evil: the human mind can kinda understand evil for a goal, with an end game, but evil just for the sake of evilness is pretty hard to grasp. You could add the whole 4e's abominations to them: they were created living-weapons made by both camps of the God vs Primordials. In this new version of the Yugoloth, they could craft abominations as weapon sold across the planes to fuel cosmic wars.
That is an interesting direction to take them, less armies and more like the Daelkyr of Eberron, crafting horrors.