Combat Maneuvers/Overrun

Action: standard action, taken during your move or as part of a charge
Target: one opponent who is no more than one size category larger than you.
Feats: Powerful Maneuvers, Greater Overrun

You can attempt to overrun your target, moving through its square.

When you attempt to overrun a target, it can choose to avoid you, allowing you to pass through its square without requiring an attack.

If your target does not avoid you, make a combat maneuver check as normal. If your maneuver is successful, you move through the target’s space. If your attack exceeds your opponent’s CMD by 5 or more, you move through the target’s space and the target is knocked prone. If the target has more than two legs, add +2 to the DC of the combat maneuver attack roll for each additional leg it has.

If your overrun attempt fails, you stop in the space directly in front of the opponent, or the nearest open space in front of the creature if there are other creatures occupying that space.