Heart of the Hero (3.5e Feat)
From D&D Wiki
Heart of the Hero [Rage]
When you rage, your heroic strength is heightened.
Prerequisite: Base Attack Bonus +15, Rage 3/day
Benefit: For each rage feat you have (including this feat), you gain 4 spell resistance while raging. Alternatively you can add 1 spell resistance per rage feat to your existing spell resistance while raging.