We do one-shot adventures over here to set up plotlines for future campaigns and we tend to use these one-shots to min-max like crazy since we tend to tone things back in actual campaigns. The thing is that I had a deadline for one of these adventures suddenly presented to me and I have very little time to go crazy with monster builds and encounters.
The characters are all 14th level with level-equivalent wealth and 20 point buy. So far what I know to expect is a character that is a dhampir magus/oracle/mystic theurge with a lifedrinker greataxe so he can deal 2 negative levels a round. Another character will be telekinetically hurling around colossal swords, and the others will be similarly arcane classes. The antagonist for this game is a 17th level antipaladin/psion gestalt made with the Psionics Unleashed rules. The story is pretty standard fare. An antipaladin is being resurrected and imbued with psychic power, he wants to destroy the world, some champions are sent to retrieve him, and this will set the stage for the upcoming campaign we'll run.
I'm not exactly sure what I am asking honestly. I just don't have the time to learn ever nuance of the PCs like I normally would and I need some help planning to mechanically challenge some advanced players.