Toughness

Toughness Enhancements
After taking this feat, you may increase its benefits by taking the Toughness enhancements, that are available to all races (Racial Toughness) and separately to front line melee classes (barbarians, fighters and paladins). Oddly Favored Souls get this enhancement line as well, probably due to being a premium/unlockable caster class. Each enhancement adds 10 hit points to the character's total.