Finally got this one! I was determined not to spend any money on this game, so I was waiting to get some of the characters recommended in this thread. However I got a bunch of Inquisitors in one Carbonite reward, so I decided to give it a try. I got my three stars by using one Tuskan Raider, which I spent some coins to get a permanent character a long time ago. I took out the left leg of the middle pig walker and while sending the Raider to hit the left leg of the left pig walker. That left the first pig walker hanging and the third pig walker intact. I then sent the Inquisitor to hit the dangling first pig walker while shooting his saber at the third walker. Bingo! Level cleared.