We've kicked around the idea that a greater god like Moradin could handle Orcus, but couldn't handle Orcus and Demogorgon together. Hence, the greater gods are cautious about picking fights with demons, because you never know if Demogorgon and Grazzt are hiding just around the corner, waiting to jump out and ambush you. That would suggest that Moradin (or any greater god, really) is maybe something like level 37 or 38. He's going to be out of the reach of even 30th-level PCs.
That might sound like a lot of cheese, giving players the ability to become gods or fight gods, but back in the days of D&D 1.0, before we started using software versioning to describe our role-playing games, this was common practice. Yes, it was cheesy to use the Deities & Demigods book as your monster manual, but it also gave players perspective. And it was fun! Gods were no longer ethereal beings who didn't meddle in the affairs of mortals. They would come down and kick you butt. If you could trick your NPC opponents or fellow players to utter the magic Cthulhu words printed in the Deities & Demigods, they might send some minions to do them in, at least until TSR was sued for copyright infringement. I just think D&D has lost it's epic edge. It feels too "low" fantasy. This kind of stuff ups the ante.
In the first adventure, Keep on the Shadowfell, there's a priest of Orcus that has to be dealt with. The adventurers are 1st level. Conceivably, some have speculated, you could turn this into a 30 level adventure path with Orcus at the end. Is that cool or what?