Shielded assault
warlord attack 1
Melee weapon
Requirement: using a shield
Target: one creature
Attack: Strength vs. AC
Hit: "2[W] + Strength modifier damage."
Effect: "Until the end of your next turn, you gain a +2 power bonus to AC, and your allies gain a +2 power bonus to AC while adjacent to you."[MP2:85]
Shielded assault is an encounter power available to warlords at 1st level.