Aim for the left side of the platform. This shot needs to be pretty exact as you will need to take out much of the platform.
Power Activation Point
Activate your power as you are about to hit the platform. There are two ways that you may succeed in getting three stars. The first way is to have your sword slash the the pig to the left, and have the tower fall to the right. The second way is to destroy the platform, and have the tower fall to the left destroying the pig. The small round metal piece would then fall to the right destroying that final pig. Both ways may work.
First Shot Result
After your jedi laser sword slash, all the pigs are dead and buildings fall. You will then be rewarded with the three star master.