Knock-Down (General)

Your mighty blows can knock foes off their feet.

(Sword and Fist: A Guidebook to Monks and Fighters, p. 7)
Originally posted on D&D tools

• Prerequisite Improved Trip, Base attack bonus +2, Strength 15+,
• Benefit Whenever you deal 10 or more points of damage to your opponent in melee, you make a trip attack as a free action against the same target.