http://forum.square-enix.com/ffxiv/t...Lists?p=449764
MNK Abl. 3 - Prevents target from executing actions or moving. MP is continually consumed while effect is active. Effect fades upon executing an action, or if you or the target sustain damage.

That'd be the balancing factor. MP drain will probably be severe, or some mobs will boast a resistance. Incredibly useful applications if you don't mind being 1 man down for a while DD-wise, imo.