Order of the Rack

Three times per day as a standard action you can target a single creature. That creature must pass a Will saving throw (DC 10 + level in this prestige class + your Charisma bonus) or become unable to cast spells for a number of rounds equal to caster level in this prestige class. At 5th and 9th levels you gain one additional use of this ability. The same effect occurs whenever you score a critical hit.