Vanguard Style (Combat, Style)Source Armor Master's Handbook pg. 13
You can bring your shield to bear against dangers that threaten your allies.
Prerequisites: BodyguardAPG, Combat Reflexes, proficiency with light or heavy shields.
Benefit: While using this style, when an adjacent ally is required to make a Reflex saving throw, you can expend a use of an attack of opportunity to attempt the aid another action to improve your ally’s Reflex save. Your ally gains a +2 bonus to all Reflex saves while adjacent to you until the beginning of your next turn.