Octolock

Make a grapple check against the target. When you succeed, the target's AC is reduced by 1. At the beginning of each of your turns, you may use a free action to reduce the AC of a target grappled with this move by 1. This may stack up to 5 times, for a total reduction of -5 AC.

The target's AC reduction resets to 0 once the grapple is released or broken.