Devolution (3.5e Feat)
From D&D Wiki
You’re nothing but an animal!
Prerequisite: , Bestial Regression
Benefit: You may permanently subtract up to 8 points from your Charisma; you now gain an equivalent bonus to your Fortitude save.
Special: If you add 4 or more to your Fortitude save, you gain a +1 natural armor bonus for every 4 points (Max +2). This does not stack with any existing natural armor bonus.