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. 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 trancievers. Further Dominion research on the subject has been slow and fruitless.
Hardened plates of assimilated mold and fungus offer infestors protection from enemy fire and would-be predators. This armor also functions 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. This can be spewed over enemy targets with dire effects.
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.
Perhaps the infestor’s most dangerous feature is the neural parasite, a 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. 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.
The infestor is a ground support unit which is capable of moving while burrowed. The infestor does not have a standard attack. The infestor's abilities are largely geared towards enemy harassment, since it can spawn infested terrans even while burrowed; if snuck behind enemy lines, one can cause havoc among workers. It can also temporarily take control of a single enemy unit with its Neural Parasite 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.
In the Heart of the Swarm campaign, infestors gain the ability to use Parasitic Domination, controlling non-heroic units permanently. Infesters also gain more damage on their Fungal Growth ability and are able to Consume other target's health for energy.
In early versions of 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.
Many zerg ground units may burrow, become invisible and may be revealed primarily by detectors, and may not move or attack. Exceptions are the roach, which may move while burrowed, the infestor, which may move and cast Infested Terran, and the baneling, which can detonate while burrowed.
Some units can unburrow via autocast, causing them to emerge and attack when an enemy moves into range.
Like many zerg ground units, the infestor can burrow. However by default the infestor can move while burrowed. The infestor can use all of its abilities 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".
The infestor takes control of target enemy unit. 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.
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.
In the campaign, the infestor's 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).
↑Blizzard Entertainment Staff. 2010-07-24. 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.