Advantageous Avoidance( Complete Scoundrel, p. 73)
You have a knack for ducking at just the right moment.
You can expend one luck reroll as an immediate action to force a foe to reroll a critical hit confirmation roll made when attacking you. You can expend two luck rerolls as an immediate action to force a foe to reroll an attack roll made against you. You gain one luck reroll per day.
Unlike other luck feats, you can use this feat after seeing the success of the roll to be affected.