Iron Heart Focus p. 68
With a last-second burst of speed, you summon reserves of mental and physical will and throw off the effects of your enemy's attack.
Your training in the Iron Heart discipline grants you excellent reflexes, mental toughness, and stamina. You can draw upon your training and focus to overcome a variety of deadly effects.
As an immediate action, you can reroll a saving throw you have just made. You must accept the result of this second roll, even if the new result is lower than your initial roll.