Mounted Onslaught

You and your mount can shatter an enemy’s line with your unyielding assault.

Prerequisite: Mounted Combat, Trample, Ride 5 ranks.

Benefit: On your turn, you can overrun more than one creature. Each overrun combat maneuver check beyond the first takes a cumulative –5 penalty. If you fail to overrun a target, your movement ends. Your mount can make only a single hoof attack against one target that is knocked prone by your overrun (not one per prone opponent).

Normal: You can perform only one overrun combat maneuver per round.

Source: Adventurer's Guide