Rat Catcher (Combat)Source Heroes of the Streets pg. 29
You have a great deal of experience dealing with the subterranean pests common in cities.
Prerequisites: Knowledge (dungeoneering) 1 rank, base attack bonus +1.
Benefit: You gain a +1 dodge bonus against attacks made by creatures at least two size categories smaller than yourself, and gain a +1 bonus to attack and damage rolls against such creatures. Additionally, you take only half damage from swarm attacks, and as a full-round action can make a single attack with a natural or bludgeoning weapon against an adjacent swarm. If the attack hits, you deal half damage to the target, even if the swarm is small enough to normally be immune to such attacks.