Stone Vise p. 85
You make a crushing blow that staggers your opponent, leaving it unable to move.
By making a powerful, focused blow, you leave your opponent unable to move. The crushing weight of your blow forces it to waste a precious moment regaining its footing.
As part of this maneuver, you make a single melee attack. This attack deals an extra 1d6 points of damage. If the creature hit is standing on the ground, your attack also drops the target's speed to 0 feet (for all movement capabilities) for 1 round. It can otherwise act normally. A successful Fortitude save (DC 12+ your Str modifier) by the creature struck negates the immobilization, but not the extra damage.
This maneuver functions only against opponents standing on the ground. A flying creature or a levitating target need not save against the speed reduction effect, but still takes the extra damage.