"Air Sweepers control the sky with strong blasts of air that push back flying enemies. Air Sweepers can only face one direction, so rotate them to maximize their effectiveness."
The Air Sweeper is a defense that shoots blasts of air at Air Troops. Although it deals no damage, it pushes back air troops, giving other defenses more time to take down these troops.
It can only shoot blasts of air in a 120-degree radius, so make sure to have it face the side of the base which is most likely to be attacked by Air Troops.
The level 6 Air Sweeper is capable of holding back a clump of balloons (any level) for an extremely long time, provided there is nothing else in range of the Air Sweeper. Use this fact to cover areas of your base you want to especially defend against balloons.
Air Sweeper can only cover a certain angle, so take advantage and attack buildings that are not covered by the Air Sweeper.
It can only push your troops back a certain distance (dependent on the Air Sweeper's level).
Slow air troops like Balloons will be devastated most by this defense as it will take a relatively long time for them to return to the building it was targeting. Combat this temporarily by using a Rage Spell to speed them up.
It can be distracted by Dragons, Healers or Minions, which can give more time for any other troops to destroy it.
The Air Sweeper undergoes a significant visual change at level 5.
When initially constructed, the Air Sweeper has four wooden supports reinforced by small, metal braces and a curved, squarish platform supporting a horn-like turret, that is tied to the platform by ropes. It also has a red air pump that compresses every few seconds to release the air used to blow back troops.
At level 2, the horn-like turret becomes larger and adds a decorative blue ring. The supports supporting the platform itself are now made of smooth stone (or metal) instead of rope.
At level 3, the four wooden supports gain extra reinforcement from extra smooth stone (or metal) braces, one on each support. It is also reinforced on the side of the platform itself.
At level 4, the platform itself is now made of smooth stone (or metal) with golden supports on each side and reinforcing the side of the platform. It also gains steel footings.
At level 5, the horn-like turret increases in size once again, this time with a black ring on it instead of a blue ring. The platform is now completely gold-plated, straps and all. The base is now reinforced as it gains an armor plating complete with spikes on each corner. The four supports are now gold-plated instead.
At level 6, the armored base is now golden, and the supports gain spikes all over them.
Added in the 30th April, 2015 update.
The Air Sweeper is currently the only defense that can push back air troops, and also the only defense that causes no damage (the Spring Trap technically causes no damage either, but it does instantly kill troops that step on it).
It is also the only defense that aims at one specific direction only.
It can be rotated 45 degrees at a time, and hence has 8 directional settings.
Its range is "1-15", which means that a Balloon attacking directly above the Air Sweeper won't be pushed back.
Upgrading the Air Sweeper doesn't increase its angle range.
The Air Sweeper attacks in a rectangular area of effect of width 5 tiles and length 14, this animation takes place over 3.5 seconds, meaning that attacking troops are unable to attack while being pushed for a maximum of 1.2 seconds.
The unit being attacked by the Air Sweeper is pushed at an angle incident to the constant curve of the attack. This means that troops (particularly Minions) will fan out when hit by an attack and may retarget separately.