Bloodletting Strike(Tome of Battle: The Book of Nine Swords, p. 75)
Shadow Hand (Strike)
Level: Swordsage 5 (Two Shadow Hand maneuvers),
Casting Time: 1 standard action
Range: Melee attack
Target: One creature
Saving Throw: Fortitude partial
Spinning your blade in a butterflylike pattern, you administer a dozen precise cuts in an eyeblink. Blood flows from your foe?s opened veins.
As part of this maneuver, you make a single melee attack. If this attack hits, your opponent takes 4 points of Constitution damage in addition to your attack?s normal damage. A successful Fortitude save (DC 15 + your Wis modifier) reduces this Constitution damage to 2 points, although the foe still takes full normal melee damage.