You strongly defend your allies.

Prerequisite(s): Bodyguard, Combat Reflexes, Vanguard Style, proficiency with light or heavy shields.

Benefit(s): 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.