Crushing Umbra (Sp)

At 10th level, an Umbral Court agent can use his touch of darkness ability at will, and the reach provided by his shadow chains increases by another 10 feet (to a total 20 foot increase). When he successfully grapples a creature with his shadow chains, the Umbral Court agent can begin constricting his victim as a free action, dealing 5d6 points of damage whenever he makes a successful grapple check. Creatures constricted in this way are also considered strangled, and cannot speak or cast spells with verbal components.