Feral Death Blow p. 87
With a primal howl, you leap into the air and land on your opponent, hacking and clawing at his neck.
You leap upon your opponent, rending and tearing with your weapons in an attempt to kill him with a brutally overwhelming assault. You grab onto your foe as you slash and hack at his neck, face, and other vulnerable areas.
To use this maneuver, you must be adjacent to your intended target. As part of this maneuver, make a Jump check. The DC of the Jump check is equal to the target's Armor Class, and does not change if you do not have a running start. If the check succeeds, you can then make a single melee attack against your foe, also as part of this maneuver. The target is considered flat-footed against this attack. If your attack deals damage, your target must attempt a Fortitude save (DC 19 + your Str modifier). If this save fails, your target is instantly slain (his hit points drop to -10). If the save is successful, you deal an extra 20d6 points of damage to the target in addition to your normal weapon damage. Creatures immune to critical hits are immune to the death effect of this strike.
If your Jump check fails, you can make a single attack normally. The maneuver is still considered expended. A failed Jump check prevents the death effect, but you still deal the extra damage.