Originally posted by Hellcow:
Of course, Orcus could be an Avatar of Katashka or one of his more powerful servant.
This was the approach I took with Demogorgon in the Savage Tide campaign. Among other things, one of the key points of the Overlords is that they are tightly bound, and that if they break those prisons they will wreak havoc on the world. With Savage Tide being a campaign in which Demogorgon plays an active role, where he has a court where he's personally attended by followers, where he's directly engaged in feuds with other demon princes - this was all at odds with the image of the Lords of Dust, where the Speakers of the bound Overlords meet in the ruins of their ancient citadels. So rather than just making Demogorgon an Overlord, I presented the idea of demiplanes within Khyber - which ultimately made its way into 4E with the idea that you can find passages into the Elemental Chaos by physically exploring Khyber - and made the demon princes rulers of these realms. The idea was that they were generals of that first war... subordinates of the Overlords, but now the mightiest spirits left unbound.
While you could make Orcus a servant of Katashka, presenting him as a servant of anything is a significant change to his flavor. My preference would be to say that he was Katashka's exarch in the first age... but now he has severed ties with the Lords of Dust and intends to steal Katashka's might for his own (a parallel to his core struggle with the Raven Queen). This gives him a unique twist for Eberron, and could end up with an interesting storyline where spirits loyal to the imprisoned Overlord work with the adventurers to fight the demon prince. Of course, it could be that Orcus is the only thing keeping Katashka from breaking free from his own prison... and if the adventurers truly defeat Orcus, Katashka will rise. Can they find a way to overcome both of the lords of death?
Originally posted by Hellcow:
Personally, I like to use as much crunchy material as I am given, so being able to map a Demon Prince for which a wealth of crunch exists (Orcus) to a Rajah/Overlord for whom there is naught but fluff (Katashka) is a positive boon.
I prefer not using the classic Demon Lord and Archdevil.
While I'd probably go with Orcus-as-ambitious-upstart if I used him... if the issue is being able to use the crunch, but wanting a campaign that doesn't feel like you're using all the same characters from core... the flip side of taking Orcus and saying "He's an Overlord" is to simply change his name to Katashka and use all the crunch as it exists. You have your cultists, the dread
Rod of Katashka, the Dark Gift of the Undying, even a renamed Doresain as one of the Lords of Dust; you're just not using the familiar name.
So essentially, the question is whether name recognition and appearance is important. If it's not, you can give all the crunch and any relevant fluff to an existing Overlord and minimize the impact on Eberron cosmology. If it is, you can just make him an Overlord, or you can find another option as described above.