Balloon is a powerful card which target buildings only. Balloon can deal a lot of damage with its bomb, also, when the Balloon gets destroyed, it will release a large bomb from the underneath and deal massive splash damage to everything nearby.
This card is most effectively used for dealing damage to Towers. Coupled with the Freeze Spell. the Balloon can do lots of damage to the enemy Towers.
When your opponent deploys the Balloon, destroy it as fast as you can otherwise your Towers will take lots of damage or you will even lose it.
Minions are extremely effective at dealing with the Balloon because they have fast movement speed and high damage.
Balloon can be distracted by any deployed buildings.