Air Defense

What is Air Defense?
Air Defense is the only defense building in the game that cannot attack ground units. It is specifically designed to be powerful against air units.

So what, I have never/rarely seen air units attacking my base? 
That might be true if you stay in low trophy range where Dragons army is not prevalent. However, at high trophy range, players are frequently using their Dragons to its extreme. Placing Air Defense outside your base basically ask for Dragons to easily annihilate your entire base.

But I really stay in low trophy range…?
It’s true that Balloon tactics is quite obsolete for many months. But don’t underestimate the possibilities of Healer in action. Putting one or two Air Defense near the middle of your base is worth it, and can prevent Healer to be safely deployed early in the battle.

This anti-air tower is deadly against flying enemies, but can’t target foes on the ground. Place it wisely to cover as much airspace as possible.

Air Defense Fact (at level 1)
Damage per second = 80
Hit points = 800
Range = 10 tiles
Damage type = Single Target
Targets = Air
Favorite Target = Any

Because of attack speed at 1.0 second per shot, Air Defense has damage per shot equal to damage per second. At level 6, it deals 230 damage per shot which takes 10 shots to take down Dragon level 3.

What is Air Defense upgrade priority? And to what level?
Because air units are not prevalent, you can focus on Splash defense then Cannon or Archer Tower before upgrade your Air Defense.

It’s hard to say what level of Air Defense you need because only time you want to upgrade Air Defense is right after you see your base was mowed down by those air army. Try to upgrade them to at least level 3 which not take much time of your builders.

Defense Tactics for Air Defense
1) Good coverage
Ideally, placing 2 Air Defenses in the opposite of side of the base, while 3 Air Defenses should create virtual triangle shape. This placement will cover the entire airspace of your base.

2) Center focus for trophy protection
To fight against heavy Dragon Army, putting all Air Defenses around your Town Hall at the center of your base is the only way to prevent from losing 3 stars. Be careful not to place them next to each other to avoid 3 Lightning Spells to destroy both Air Defenses at once.

Attack Tactics against Air Defense
1) Anything!
Just attack Air Defense with ground units, pure and simple. If your army combination contains only ground units, Air Defenses become only a meat shield for you to destroy.

2) Swarm!
While it’s not cost effective, without splash damage, you can swarm Air Defense with lots of Minions.