Reckless Offensive( Races of Faerun, p. 167)
You lower your guard in order to make a telling attack.
Power Attack (PH) , Base attack bonus +2,
On your action, before making attack rolls for a round, you may choose to take a -4 penalty to your AC during the round to gain a +2 competence bonus on all melee attacks in the same round. The penalty to AC and bonus on melee attacks apply until your next action. You cannot use Reckless Offensive with ranged attacks.