Down Like Dominoes (Ex)

When you successfully trip a foe, as a free action you can attempt an additional trip attack against a creature adjacent to the first foe tripped at a –4 penalty. The adjacent creature must be no more than one size category larger than the creature you just tripped. If this second trip is successful, you can continue to attempt to trip creatures as long as they are adjacent to the last one successfully tripped, taking a cumulative –4 penalty on each trip attempt after the first. In a round, you can trip a number of creatures equal to half your tier in this way, and only until your first failed trip attempt. You don't provoke attacks of opportunity for tripping additional foes with this ability, and if you fail a trip attempt after the first there's no chance of you tripping yourself.