Ironclad Reactions (Armor Mastery, Combat)Source Armor Master's Handbook pg. 17
You are able to quickly react to attacks.
Prerequisites: Base attack bonus +6 or fighter level 4th, armor training class feature, proficiency with medium armor.
Benefit: Once per round when a foe successfully hits you with an attack of opportunity, you can expend a use of an attack of opportunity to take a 5-foot step. You can do this even if you have already taken a 5-foot step.Source Armor Master's Handbook pg. 21 (Amazon)
You can spend 3 stamina points to use this feat even if an attack of opportunity against you misses. (See page 17.)