As its name implies, the Water Balloon is a simple, but huge blue balloon filled with water. At first glance it seems like a primitive weapon, but its qualities are invaluable against Destruction Troops which short-circuit when poured with water. As such, it is a weapon that these robots fear more than anything.
In gameplay, the Battle Trumpet can used to damage Destruction Troops. It can be found at fixed points throughout the game or be dropped by destroyed Treasure Minions. When found, it can be picked up by the playable characters. When used, it is thrown at a selected place, where it will explode and spill water around it, deactivating any Destruction Troops for a time, thus making it easier to eliminate these enemies. This makes the Water Balloon a reasonable support weapon.