It takes a bit of patience, but it pays off at the end. You can simply destroy all of the Air Defenses, Archer Towers and Wizard Towers, then deploy a single Balloon.
Note that this technique is completely ineffective when dealing with air troops, because the Balloon's death splash only affects ground troops. Group all the Clan Castle Troops together and as the Balloon gets destroyed by the defending troops it will use the death splash to chip or wipe out ground Clan Castle Troops such as Archers or Wizards beneath.
Balloons are "promoted" Wall Breakers that now attack from a hot air balloon.Balloons are the sixth overall troop unlocked in the Barracks, and is the first aerial unit unlocked in the Home Village.