Merciless Beating

Combat

When you have the numbers on your side, you can lend your strength to the group to give your shared enemy a savage pummeling.

Prerequisite: Int 13, Combat Expertise, Gang Up.

Benefit: Whenever you and two or more allies threaten an opponent, you can choose to forgo your flanking bonus to grant each of your allies a +1 flanking bonus on their attack rolls against the threatened creature. This bonus stacks with any flanking bonuses your allies might already have.

Source: The Harrow Handbook