Rending Swarm (Combat, Teamwork)Source Blood of the Beast pg. 23
Together, you and your allies tear through enemies’ defenses. Dex 15, Rat Stack, swarming racial trait.
Benefit: You gain a +1 bonus on all melee damage rolls for each allied creature you share a square with that also has this feat.
If two or more allies sharing a square have this feat and hit the same adjacent creature in a round, they tear it in different directions, dealing additional damage at the end of the round. This rend attack deals an amount of damage equal to 1d6 + the highest Strength modifier of all qualifying allies in the same square who struck the target this round.