Defended Movement (Combat, Shield Mastery)Source Armor Master's Handbook pg. 18
You deftly block attacks with your shield while moving through battle.
Prerequisites: Shield Focus, base attack bonus +6 or fighter level 4th.
Benefit: You gain a +2 bonus to your AC against attacks of opportunity.
Special: Defended Movement counts as both Dodge and Mobility for the purposes of feats that have Dodge and Mobility as prerequisites.Source Armor Master's Handbook pg. 20 (Amazon)
You can spend 3 stamina points as an immediate action to increase the bonus to your AC to +4 against a single attack. (See page 18.)