Well, the flip side of save-boosting would be safe-debuffing. A sorc could go arcane spellsurge, followed by quickened limited wish+heightened spell (effectively getting +7 to save dc).

A twinned, maximized enervation would inflict 8 negative lvs, which means -8 to all saves as well.

Some conditions, like sickened, also impose save penalties, if you can get them to affect the monster successfully.