Rampaging Bullrush

 
Prerequisite(s): Ability to Rage, Large size or larger, Improved Bullrush
 
Benefit: While in a rage, you can attempt to knock down any creature that you successfully bull rush (that is, that you push back at least 5 feet with a bull rush attempt). You take a -4 penalty on your Strength check to bull rush the opponent, but if you win, the opponent is knocked prone at the end of the bull rush.
 
Source: Races of Stone