Bloodletting Strike p. 75
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.