Drain Vitality p. 77
A faint nimbus of sickly gray shadow surrounds your weapon. When you attack, this shadowy aura flows into the wound you inflict, sapping your opponent's strength,vitality, and energy.
As part of this maneuver, make a single melee attack. If this attack hits, you deal normal melee damage and the target must make a successful Fortitude save (DC 12 + your Wis modifier) or take 2 points of Constitution damage. A successful save negates the Constitution damage but not the normal melee damage.