[Imperialus]

hrm... Interesting concept, but what are your ideas for fitting him into the campaign? Remember, in Daemonforge good and evil both arrived at the same time during the first fiend war. They always have exsisted. If he is some arch fiend then he would have to be incorperated as another fiend lord, or he would have to be resideing in hell right now waiting for the gates of dusk to open again.

Also another important thing to point out, is I belive it was decided that Daemonforge does not exsist in a multiverse. It is more like the center of a cube with the 4 elements boardering on the sides, heaven above, and hell below. Unless his powers were scattered to the elemental planes I don't really see where they could go. Technically speaking it would be impossible to travel from Daemonforge to Dragonlance, Darksun, Forgotten Realms, SpellJammer or anything like that. It exsists as the sole prime material plane in exsistance in this universe.

I know I say this to a lot of new people, but I'm honestly not trying to rip appart your ideas. I think he's actually a really cool character concept, perhaps as a sort of "sleeping fiend lord". If you were to work his fall into the background story somehow. Perhaps he could have even been killed in the first fiend war before mortals even existed and he could be a sort of legendary threat who's true existance could only be found out by searching through old ruins and manuscripts that had survived from that time period. Finding and distroying him could even be the mission of a secret society, (The "Opposition of Yogsathoth" as you called them) under the command of probably either the Grey King, or The Pale Lord who are the two most studious of the patrons.

Anyhow those are just ideas, Hopefully we can figure out a way to work him into the campaign without changeing your vision of him too much.