So it was pointed out to me after fairly extensive playtest that the corruption rules in my Age of Conan books are B.R.U.T.A.L. By the time a sorcerer hits second level, he's almost guaranteed to already be irredeemably evil and has so many penalties that it's pointless to try save against corruption anymore.
It's true, too. If every time you fail a save you rack up a cumulative -1 penalty to future saves, it takes only three spells to wipe out the Sorcerer's +3 to save vs. Spell Magic when making corruption saves. Three spells. That's rough, even for Conan.
Thus, I am tweaking the corruption save rules as follows:
For every three levels of corruption gained--that is, every time the sorcerer would ostensibly drop a rank in alignment (regardless of whether he actually does drop)*, he suffers a cumulative -1 penalty to all future corruption saves.
*Remember, if a Sorcerer begins play as Neutral (Unaligned), he still has to fail 6 saves before he would drop to Neutral (Balance). Just because his moral code is naturally different than others does not mean that he's already corrupted by evil. Optionally, you could implement the first penalty upon the first failed save, to represent the beginning of the path of corruption, and then implement additional penalties for every multiple of three thereafter.
The best way to handle this is to track levels of corruption on the character sheet, marking a -1 penalty advancement with each level of corruption gained. Thus, a progression on the sheet might look like this, with a box checked every time a save is failed:
[ ] (-0) (-1)
[ ] (-1) (-2)
[ ] (-2) (-3)
[ ] (-3) (-4)
[ ] (-4) (-5)
The second set of numbers represents the optional progression.