Vanguard Ward (Combat)Source Armor Master's Handbook pg. 13
You strongly defend your allies.
Prerequisites: BodyguardAPG, Combat Reflexes, Vanguard Style, proficiency with light or heavy shields.
Benefit: While using Vanguard Style, when an adjacent ally is attacked or required to make a Reflex saving throw, you can expend a use of an attack of opportunity to use both Bodyguard and Vanguard Style to protect that ally. You can also lose your shield bonus to AC to grant your ally a shield bonus to AC of the same value for as long as that ally gains a bonus to Reflex saves from Vanguard Style.