You easily tear your enemies limb from limb with your natural attacks.
For example, a troll that has this feat can rend when it hits with one claw attack, while a girallon that has this feat must hit one target with two claw attacks to rend. You can only make this rend attack once per round.
Pathfinder Roleplaying Game Ultimate Combat. © 2011, Paizo Publishing, LLC; Authors: Jason Bulmahn, Tim Hitchcock, Colin McComb, Rob McCreary, Jason Nelson, Stephen Radney-MacFarland, Sean K Reynolds, Owen K.C. Stephens, and Russ Taylor.