Oh No Power Corrupts
This campaign is nominally set in Eberron. Since it involves characters of around epic level, however, it’s hardly limited to that plane.
(Which reminds me that I was recently informed that Eberron’s “cosmology” is so fundamentally different from the standard D&D’s that the planes don’t even exist in the same way, and that it’s a distinctly different world than blah blah blah. Whatever. My game is: Eberron has everything.