Awesome Blow

 
Prerequisite(s): Str 25+, Large+ size, Power Attack, Improved Bullrush
 
Benefit: You can take a -4 to your hit roll in exchange for a blow that sends a smaller opponent flying 10' if they fail a reflex check vs DC = Damage Dealt. Opponents so affected are prone at the end. If an obstacle stops the creature in mid air, it takes an additional 1d6 damage.
 
Source: Monster Manual, Monster Manual 3