Greater Trip (Combat)
You can make free attacks on foes that you knock down.
Prerequisites: Combat Expertise, Improved Trip, base attack bonus +6, Int 13.
Benefit: You receive a +2 bonus on checks made to trip a foe. This bonus stacks with the bonus granted by Improved Trip. Whenever you successfully trip an opponent, that opponent provokes attacks of opportunity.
Normal: Creatures do not provoke attacks of opportunity from being tripped.