GUY, 9 snipers, 3 droids and Chewbacca/Leia (Johhar, level 4 or above) is great. Seperate em into 3 squads, 3 snipers and one droid one squad, and deploy them at three seperate places on the map. Guaranteed 50% success. (This is for level 7). Also, deply the hero with one of the squads, to destroy the turrets.