Infestors are carried by sturdy legs that secrete a corrosive substance that softens the soil and allows them to burrow in the blink of an eye. Unlike most zerg strains, infestors have the ability to move while burrowed, and can do so at an astonishing speed. Writhing sensory tentacles that extend from the infestor's jaw serve as a secondary, albeit more powerful, set of eyes and ears by means of thousands of microscopic growths that function as biological transceivers. Further Dominion research on the subject has been slow and fruitless.
Within the Leviathan infestors, the defensive structures of the base creature are more pronounced. The primal zerg utilize infestors as well, but they are often the targets of larger creatures in their own pack. These infestors have evolved thickened plating along their back to protect themselves. Those infestors enslaved by the Cerberus Program were implanted with a titanium infrastructure to improve their survivability.
Infestors are known to ingest infested marines to use as terror weapons on the battlefield, carrying them to a combat zone. The marines are stored in thick flesh cavities until the infestor regurgitates them to face their former compatriots, or anything else that might pose a threat to the Swarm. These infested marines can pop right out from the ground if the infestor is burrowed. Infestors are also capable of harboring larva and spewing them at enemies.
Perhaps the infestor's most dangerous feature is the neural parasite, a multi-mouthed symbiotic creature living within infestors that, when spat, attaches to an enemy and controls its mind for a short period of time. This is inserted through a parasitic stinger, a flexible appendage that is capable of boring through both natural and organic plating. The parasite then is then inserted directly into the target's central nervous system. The amorphous, multi-mouthed parasite cannot survive for long within a foreign body, but whatever horrific deeds the host carries out while under the influence of the Swarm will leave everlasting scars. The neural parasite embeds itself near the top of the spine of the victim, and the parasite's host can still communicate through the creature's native language to their former allies. Seeing the immense potential of this parasite, the Queen of Blades carried out incubation of new strains capable of living longer outside of their host.
Hardened plates of assimilated mold and fungus offer infestors protection from enemy fire and would-be predators. Upon developing the fungal growth mutation, this armor can also function as a weapon, as the infestor can turn the inner layer of its carapace into a viscous fluid that breaks down matter in seconds and immobilizes anything it comes in contact with. The fluid is sprayed over an area, and any enemy it touches suffers both damage and immobilization. The growth reveals both cloaked and burrowed enemies.
The infestor is a ground support unit which is capable of moving while burrowed. The infestor does not have a standard attack. It can also temporarily take control of a single enemy unit with its Neural Parasite ability. Workers taken by neural parasite can construct buildings while under the parasite's control, allowing the player to potentially have the army of another race. The infestor can also cover allied units from air attacks with its Microbial Shroud ability.
When an infestor moves, it leaves behind a trail of slime. When burrowed, visible cracks on the surface can be seen by its controlling player.
Upon death, an infestor's abdomen will swell and the explode. When killed with fire, it will flail its front legs and then roll onto its side.
Like many zerg ground units, the infestor can burrow. However by default the infestor can move while burrowed. The infestor use Neural Parasite and spawn infested terrans while burrowed. It moves faster under the creep.
Infestors cannot burrow underneath structures, not even destructible rocks or pylons. The pylons project a strong magnetic field which makes the ground beneath them impenetrable by "mortal means".
Units maintain their upgrades and special abilities while controlled. Control reverts to the original player if the infestor is killed, when duration ends, or when the range between the infestor and the controlled unit grows too large.
Controlled probes and SCVs can build structures; the SCV will leave a structure unfinished if it reverts during the construction. Affected drones cannot mutate structures. Larva can be morphed, but hatched units return to enemy's control once the effect has worn off.
Affected units cannot be loaded into transports, and ability cannot be used on transports carrying units. Affected units can be recalled by a Nexus or Mothership.
Ability can be used on enemy infestors. Units mind controlled by affected infestors remain under player's control for normal duration, even after affected infestors revert to opponent's control. Heroic units (such as motherships cannot be controlled.
An infestor launches a projectile with a speed of 15; enemy units within the area of effect (2.25 radius) have their speed reduced by 75% and suffer 30 damage over 3 seconds. Cloaked and burrowed units are revealed.
Fungal Growth stops the use of Blink, Tactical Jump and prevents units from burrowing or unburrowing. Affected units can not be loaded into buildings or transports.
In the campaign, the infestors' neural parasite is permanent and doesn't need to be channeled, and the infestor has the consume ability from the viper. They cannot create infested terrans; these are instead generated through plot-based mechanics (the virophage).
In the Heart of the Swarm campaign, infestors gain the ability to use Parasitic Domination, controlling non-heroic units permanently. Infestors also gain more damage on their Fungal Growth ability and are able to Consume other targets' health for energy.
The infestors' fungal growth ability no longer hits air units, and units hit on creep will be slowed instead of rooted, but will not be able to move off the creep. Its overall radius was increased.
In Legacy of the Void infestors gained the Aggressive Mutation ability. This grants a flat damage bonus to allied units, making it especially effective when used on zerglings and other cheap units with a low cooldown. This ability was removed in the final version of the game. In patch 3.8, infestors gained the ability to use neural parasite and fungal growth while burrowed. In Patch 4.11, the infestor lost its Infested Terran ability in favor of Microbial Shroud.
↑Blizzard Entertainment staff. 2010-07-24. Units: Infestor. Blizzard Entertainment. Accessed 2010-07-24.
↑No, they cannot move under buildings. The ground is too compacted from the weight of the structure and the Infestor cannot tunnel through. Even Protoss Pylons make everything really hard to move through because a strong magnetic force from the Pylon makes the ground beneath it nearly impenetrable by mortal means.
It's not really practical for the gameplay. You get "units inside units" if the the Infestor could hide under structures which is never a happy place to be. Selection gets difficult, targeting becomes challenging, etc. Cavez. 2009-02-26. (Question) Infester movement under buildings?Battle.net StarCraft II General Discussion Forums. Accessed 2009-02-27.