Make a standard Creature Powers attack at an opponent's arm (or equivalent manipulative limb). If you hit and your Outcome + Magic matches his Constitution, you pull a limb right off.
Whenever you cause WoundPoints equal to your opponent's Constitution with an unarmed attack, you rip an arm (or similiar limb) right off your opponent.
The opponent loses the use of the limb and will lose a number of Shots equal to the WoundPoints inflicted. The limb can be used as a soft club ( damage of Strength +2), with a special +3 action value bonus against its former owner. It will hold on to whatever it was holding before. If holding a weapon or equipped with natural weapons, you can use that damage add instead, and you get to use that equipment with your Powers. It is concevably possible to rip someone's arm off when they are using a toolkit, and then ue the tool and your Powers to repair things.
This schtick is supernatural and because of that the limb can be put back into place by its owner as a 3-shot action (once recovered). If not put back on, it will spoil in an hour or so.