dnd4
Interposing Shield
Fighter Utility 16

Using your weapon or shield, you block an attack made against a close ally

Encounter ✦ martial

Trigger: An adjacent ally is hit by an attack

Effect: The ally gains a +2 power bonus to AC and Reflex defense against the triggering attack. If you are using a shield, increase the bonus to +4

Interposing Shield is an encounter power available to fighters at sixteenth level.[PH:82]