Simply aim for the blocks blocking the TNT bomb in the cave to the right of map. Watch out for the laser gun as you will have to find the right timing to launch your shot.
Power Activation Point
Activate the power as you are about the hit the blocks. Your goal is to trigger the bomb.
First Shot Result
The bomb is triggered, sending the round metal balls to the sky, landing and killing all the pigs. You will then obtain the three star rating.