Believed to be the nesting form of the Mutalisk, this is a secondary stage that has a much thicker armored carapace and a longer ranged plasma attack. The Guardian is, however, noticeably slower than the Mutalisk, and as such is used primarily to defend the vulnerable Zerg Larvae.

Producible once the Spire is evolved into a Greater Spire, the Guardian is morphed from the Mutalisk. Once the transformation is complete, the Guardian form is permanent and the Mutalisk is no longer recoverable.

The Guardian is one of the most powerful Zerg assault units with an incredible attack range and an attack that inflicts a full 20 base points of normal damage. In addition to the awesome attack potential, the Guardian also has 2 points of base armor, making it more resistant to attack than most units.

Guardians make great blockade breakers, particularly against Terran Siege Tank/Bunker combinations and Protoss Photon Cannon clusters. However, when approaching these blockades, use the terrain to your advantage (as described above) and always target the perimeter units/structures first. Failing to do either can be devastating to a Guardian force should they wander into the attack range of enemy units, nullifying any advantage they might have had.

The powerful Guardian attack can be very useful in eliminating specific targets while support units distract and divert an opponent's attention. Use the Guardians to eliminate the more powerful enemy units quickly (i.e. Siege Tanks, Reavers, Ultralisks, etc.) so that not only do the Guardians have less to worry about, the support units will have a better chance of surviving and causing more damage.

The Guardian does have a few weaknesses and these keep it from being a self sufficient unit. First, Guardians have no defense against attack from aerial units since their Spore attack works only against ground targets. This makes them particularly vulnerable to attack from Scouts, Corsairs, Carriers, Wraiths, Valkyries, Battlecruisers, Mutalisks and Devourers. Also, Guardians move very slowly and have a difficult time retreating from a battlefield when the tide turns in the enemy's favor. To alleviate these problems, always keep a support group of Mutalisks or Hydralisks nearby to deal with any unforeseen circumstances.

Uprades

Flyer Attack - Each upgrade adds +2 to the Flyer Attack for a total of +6 when fully upgraded.

Flyer Carapace - Each upgrade adds +1 to the Flyer Carapace for a total of +3 when fully upgraded.