Winding Strike (3.5e Martial Artist Maneuver)
From D&D Wiki
In battle, the first attack is most important. If you can get in a quick strike, you will find your enemy's focus lessen.
Level: Aggressive 1
Type: Action (Attack)
Description: A foe damaged by your attack (either unarmed or with a melee weapon) must succeed on a Fortitude saving throw. A defender who fails on this saving throw is stunned for 1 round. Furthermore, if the first successful attack in a battle against a particular opponent is a winding strike and the opponent fails his Fortitude save, he must also make a Will save or become winded for an additional 2d4 turns after recovering from the stun effect. A creature that is winded takes a -1 penalty to attack rolls, saving throws and skill checks.