Balloons are "promoted" Wall Breakers that now attack from a hot air balloon. They drop bombs on the villages with a large area splash damage, but can be easily taken out by any anti-air defenses (such as the Air Defense).
Balloons are slow-moving aerial units that do devastating amounts of splash damage to ground targets.
Balloons drop to the ground then explode, dealing additional damage when destroyed.
Balloons prioritize defensive structures above all other targets, and will bypass all other types of enemy buildings and troops while any defenses remain on the battlefield. This is true even if they are under attack by enemy Clan Castletroops, heroes or Skeleton Trap skeletons. Note that like all troops that prioritize defenses, Balloons do not consider the Clan Castle to be a defense regardless of whether or not it contains enemy troops, but do consider the defending Grand Warden to be a defensive building. Once all defenses are destroyed, Balloons become like any other troop with no preferred target; they will attack the nearest building to them regardless of type, and will turn and attack enemy units if they become aware of any nearby.
Balloons can be used to kill Clan Castle Troops due to its death splash, although it primarily attacks defenses. Group all the Clan Castle Troops together and as the Balloon gets shot down by the Clan Castle Troops it will use the death splash to its advantage to kill the Archers and Wizards beneath. Note that this technique is completely ineffective when dealing with air troops, because its death splash only affects ground troops.
Important note: In many cases a single Balloon will take enough time to destroy the remaining buildings (commonly in the Single Player Campaign maps) that your game will time out due to inactivity, which will cause your attack to end prematurely and be unsuccessful (regardless of how many stars you had earned prior to that point). To prevent this from happening simply change the view every few moments (by panning or zooming).
When raiding other players, time is limited, so make sure you take out all the Air Defenses and other defensive buildings that can target Air Troops (e.g. Archer Towers, X-Bows) quickly so you can sweep up the raid.
Groups of five Balloons or more can usually overwhelm an Archer Tower. Nine Balloons is generally assured destruction unless there are Air Bombs or an Air Defense nearby.
If Elixir and time are not priorities, dropping a Dragon or a Lava Hound near an Air Defense before deploying Balloons can protect them from being attacked for a significant amount of time, much like Giants can occupy a Mortar.
You can also send Balloons after Air Defenses themselves, but this isn't recommended if the Balloons have a long distance to fly for they will be shot down quickly.
Although Balloons are slow moving, their damage is excellent; a good option is to speed them up with a Rage Spell or a Haste Spell. "Rage-Balloons" is an effective, if not often used, strategy (the only drawback is the time to train them).
Balloons deal a lot of damage on their own and the extra bonus from the Rage Spell isn't really needed and can be switched up with two Haste Spells.
Destroy the Air Defenses, as their sole purpose is to destroy air units (and they are very good at it). Mistakenly placing a Balloon while the Air Defense remains active will cost you!
Balloons can be very strong if you know how to use them, but never train an army of only Balloons; Clan Castle troops can make short work of them!
Generally, Balloons are relatively decent as a defensive unit: if a player is attacking only with troops that cannot target air units (Barbarians, Giants, Goblins, etc.), the Balloon is perfect for defending as it cannot be destroyed except by Lightning Spells. It is especially effective against Barbarians and Goblins as it does splash damage.
From a defensive standpoint, it takes quite a few Archers to take out the Balloon, which effectively weakens the raid. Its only major weaknesses are Dragons and Minions, both of which can destroy it easily without fear of counterattack. A single similar-level Wizard (up to level 3) is also able to destroy a Balloon due to its high damage output, but only if it has sufficient range to fire twice before the Balloon closes (the Balloon will destroy the Wizard in one shot). Beyond level 3, two Wizards would be required.
At lower levels the Balloon has such low HP that it is vulnerable to being taken down by two Air Bombs. Consequently a great way to defend against lower-leveled Balloons is using a grouped pair of Air Bombs; they can take an entire group out before they get a chance to get healed with a Healing Spell.
Appropriately, at each level the Balloon pilot resembles a similar-level Wall Breaker.
The Balloon undergoes significant visual changes at levels 3 and 6.
At level 3, the Balloon receives wooden armour attached to the sides of the envelope underneath its rigging.
At level 5, the Balloon's basket gain golden spikes attached to its side and the bombs it drops become golden in colour.
At level 6, the Balloon's red envelope turns to black with a white skull on it, and the wooden armor become gray-black steel.
The 17 Apr 2013 update granted the Balloon the ability to explode and deliver splash damage when it is shot down.
Although piloted by former Wall Breakers, Balloons do not use kamikaze-style attacks (though they do still explode on death).
The Balloon's damage upon death is the same as its DPS.
While most levels of Balloons drop bombs that are carried by Wall Breakers of the same level, the level 6 Balloon does not drop barrels, but gold bombs instead.
Each upgrade above level 2 increases the Balloon's damage by 50%.
Currently, the Balloon is the only air troop that has no wings.
If a Balloon's death causes the battle to end (if there are no more non-Healer troops, Heroes, Lightning Spells or Earthquake Spells remaining), the Balloon will appear to drop to the ground (as it should) but it will not deal any damage upon death.
The Balloon is the only troop with a death animation. When anti-air defenses defeat a Balloon, it will fall to the ground, damaging any buildings within its death damage radius.