Falling Sun Attack( Tome of Battle: The Book of Nine Swords, p. 31)
The discipline of the Setting Sun teaches you how to turn an opponent's strengths into weaknesses. You can identify precisely the correct spot on your opponent's body to deliver a stunning attack.
Stunning Fist (PH) , one Setting Sun strike,
Distant Horizon (ToB) ,
You can declare any-Setting Sun strike delivered with an unarmed strike to be a stunning attack. In addition, add 1 to the save DC of your Stunning Fist attacks and 1 to the save DC of your Setting Sun strikes. Using this feat expends a use of your stunning attack ior the day.