You can rend opponents you hit with your claws.
Prerequisites: Two claw attacks, Str 13, Power Attack, Snatch, size Huge or larger.
Benefit: If you strike the same opponent with two claw attacks, you automatically deal extra damage equal to that of two claw attacks plus 1½ times your Strength bonus. You cannot grab an opponent at the same time you rend that opponent.
Source: Draconomicon, page 73.