Defender is the basic and cheap anti-air missile tower. Built by all T1 cons it is able to take down light aircrafts. Not enough to stop bombing/gunship runs. Always have one or two in your base to protect yourself from humiliating com-dropping tactics.

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Light Laser Tower is the cheapest and fastest to set up form of defense. Built by the Commander and all T1 cons. It is reasonable to build one or two to protect your T1 base against early scout raids. When expanding, protect your metal extractors with those. Two LLT's are often enough to stop a hostile Commander push.

Beamer is a tracking-laser turret with the highest DPS among all T1 defensive structures. Built by all T1 land/air cons has a very precise aim and decent range. Use it to overshoot rocket bots, LLTs, and deal the greatest chunk of damage to raiding units. It may even kill a walking commander before it gets D-gunned.

Packo is a pop-up medium range anti-air tower. Built by all land/air cons it It stands a chance against heavier T1 aircraft. Its pop-up and cloak abilities make it a difficult target for land infantry. As a cool gimmick it may be cloaked to trick your opponent into thinking that you have insufficient Air defense and trap his aircraft when as they come.

Sentinel is a high-energy laser turret. Built by all T1 cons it overshoots every T1 unit except artillery vehicles. 

Despite the long range and heavy damage it is hopeless when built alone. 

Always incorporate it within other defensive structures.

Chainsaw (Bomb-Resistant Medium-Range Missile Battery) is an expensive T1 anti-air tower that serves a very situational purpose. Built by all T1 land/air cons it has the highest DPS and range among all T1 AA. When placed properly it may even take down a Liche (Nuclear bomber).

Guardian is the T1 long-range plasma battery. Built by all land/air cons it serves a very situational purpose.

It can be set to high trajectory for bigger damage and AoE, but lower fire rate and accuracy. This is helpful when you have to shoot over obstacles.

It can overshoot all T1 structures and units, but keep in mind that it requires a lot of metal to build. In most cases this metal is better spent into mobile units or tech advancement.

Building it to protect your base area is usually a big waste, better resort to laser turrets for this purpose. However, making it on extended front, or in range of enemy economy may end up winning you a game.

Useful on hills, for taking down strategic targets. Pretty useless when T2 arrives. Consider reclaiming it to get your metal back.

Pit bull is a cloakable pop-up gauss cannon that has a great DPS and range for considerably low costs. Built by all T2 land/air cons it serves the most basic role among the defenses – to pump in big DPS. Its pop-up and cloak ability makes it a great way to surprise attacking troops with unexpected damage source.

Flakker is a short range anti-air turret that can deal ludicrous amounts of damage in a big radius (AoE). Built by all T2 land/air cons it is able to shatter most aircraft within its range. Best Damage per second/cost ratio among all AA, but also - short range. Build it around strategic point-targets and front-line defenses.

Protector is an ICBM interception missile silo. Built by all T2 land/air cons it is able to cover a decent area spanning over your base and surroundings. It protects you from long-range nuclear missiles (not tactical nukes). Takes 90 seconds to stack up one missile. Always make one after the 15 minute mark and be careful as it may be EMPed by spies or ARM EMP silos.

Mercury is a long range anti-air missile battery. Built by all T2 land/air constructors it piles up to five missiles (14s to produce one) that can shoot across great distances and deal ludicrous damage to aircraft. A single missile can take down most air units. Great for countering Liche (atomic bomber) runs, when used with SET TARGET command. Built on the extended front-line, thanks to its range it may be used to slowly dismantle enemy’s fighter wall.

Ambusher is a T2 cloakable pop-up long range plasma battery. Built by all T2 land/air cons it is able to protect your defense line from artillery units and dismantle enemy’s defense line. Out ranges all T1/T2 units except Annihilators, Berthas etc. Build on hills to take advantage of extended range and take down strategic targets.

Set to High-Trajectory it deals more damage in a larger radius (AoE), but it will shoot slower.

Another use case is to stop Snipers, which get outranged by these. Be sure to provide good line of sight for it, for good aiming.

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Annihilator is the most powerful T2 defense structure. Built by all T2 land/air cons, it packs a bad-ass long-range tachyon laser that can one-shoot all T1 and T2 mobile units. It overshoots all other defense structures and may even take down T3 mechs. Takes 1500 E to shoot. You can put it on “off” in order to hide its turret in its heavy duty armor that can withstand tons of damage.

Big Bertha is a long range plasma cannon (LRPC). Built by all T2 land/air cons it is able to shoot targets across the map. On most battlefields placing it on the front-line enables you to take down buildings in enemy’s base. Not very effective on mobile targets. When built, it immediately becomes a priority target for your foes, try to keep it safe. Can be countered with Plasma deflectors, but those come at a high cost.

Vulcan is the ultimate weapon of mass-destruction. Built by all T2 land/air cons it is basically a spinning wheel of Big Bertha plasma cannons that can shoot across the map and tear down whole bases. It takes giant resources to build but when it is in place it basically wins you a game. 

However, remember that it also consumes great amounts of energy to shoot (14500 energy/shot), hence don’t build it if your income is below 35k energy.

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