I think it would be utterly foolish to even aim for something like that. Better to make a qualitative campaign that settles for max lvl 12 or something similar than trying to cram out spells that are freakishly hard to implement in a computer game (I am looking at you "Wish", amongst many others). Not to mention enemy types and such. Also, personal preference: I don't like getting to the point where shit becomes ridiculously epic. That crap bores the heck out of me. Hell, I even think level 12 is way too high, but I can at least accept something like that.
