Reactive Strike

Trigger A creature within the monster's reach uses a manipulate action or a move action, makes a ranged attack, or leaves a square during a move action it's using; Effect The monster attempts a melee Strike against the triggering creature. If the attack is a critical hit and the trigger was a manipulate action, the monster disrupts that action. This Strike doesn't count toward the monster's multiple attack penalty, and its multiple attack penalty doesn't apply to this Strike.