@Goldfish @TalonofAnathrax @TotallyNotEvil Now the inevitable, what would you build be if it was every-man-for-himself and you could select Tier 2-3 Classes, PrCs allowed, with the caveat that all of the Big Bads know who you are and aproximately a brief overview of what you're capable of (no more than someone who spent a lot of time dumping divinations on someone, anyway)? With Tier 2 I think you could honestly still experience a challenge, esp. if you don't get to outright suckerpunch anyone, but then with access to PHENOMENAL COSMIC POWER and the ability to abuse meta-knowledge it's honestly more a matter of how you choose to win.
Also with access to entire spell Arcane or Divine spell lists the multiverse is your oyster, assuming metaphysics are forgiving, so you could just peace outtie. Probably why they specified nothing above Tier 4 in the first place.