Aim and launch at the middle of the stage. You do not need to trigger the bomb for the three star mastery. All you need to do is to kill all the pigs with your one single shot.
Power Activation Point
Activate your light saber after you have landed into the block. Be careful that you will have to activate it within 1 second or so.
First Shot Result
The buildings tumble down and kill all the pigs. You will then end the stage with the three star mastery rating.