Needs review
Source: Pathfinder: Ultimate Combat

Description: You can barrel into your opponent and follow this with an attack.

Prerequisites: STR 13, Power Attack, Improved Bull Rush, Base Attack Bonus +6

On your turn, you can perform a single bull rush combat maneuver in place of one of your melee attacks. You must choose the melee attack with the highest base attack bonus to make the bull rush.

Normal

A bull rush combat is a standard action.