Find your base. This strategy requires a non-centralized air defense that is easy to take down.
Spam all 18 of your giants on one spot very close to the first air defense that you wish to take out. When the defenses are distracted, send in a few wall breakers to break through the walls. Your giants should move to eliminate the air defense.
Right when the air defense goes down, deploy your Healer right on top of the mob of giants. Deploy a heal spell if needed.
Spread a few of your archers around the map to get rid of any extra defenses.
Once your Healer starts moving towards the other air defenses, spam several archers to get rid of the air defense. Pile on the balloons if needed. The balloons are not key to the attack.
Your giants will simply go around the base and wreck every defense in their path. The healer will keep the giants in the game. If the giants meet a road bump, drop a rage spell to madden your giants and make them go beast mode. Heal your giants with a healing spell if they are less than half health.
Spam balloons on cannons and mortars to help out the giants.