Infestor (NOTD)

Infestors are slow moving, yet durable creatures. Five will spawn at random locations throughout the map, including inaccessible areas such as "islands" of terrain. This is true for all Campaigns, Difficulties, and Survival Mode. Killing an Infestor will grant every team member a healthy amount of in game experience. Killing all of them will complete a bonus mission. Another benefit of killing Infestors is it reduces the spawn rate of the zombies. The spawn rate is reduced by 2 zombies per minute per Infestor killed. Knifing them will conserve ammo and slow them down for the rest of the team but you should move away from it immediately if it lays a clutch of Baneling eggs.

Team Experience
Killing Infestors will grant 150 experience to the killer and 100 shared experience to the team. This is especially useful in the early game as it can account to and entire level. Killing the Infestors as quickly as possible will proportionately help the team the most.

Frenzy
In Nightmare Mode, an Infestors will move faster with every hit they take. Every time a marine hits an Infestor (including knife), the Infestor will move 1% faster, to a maximum of 30%. This also affects the speed of the Infestor while it is burrowed, and can therefore allow the Infestor to easily escape from pursuing marines, and spawn its deadly banelings.

Parasitic Incubation
On higher difficulties, Infestors will spawn 3 Parasites upon death. If they die while burrowed Parasites may not spawn. Normally there is a slight delay as to when the Parasites spawn, but on Nightmare, no such delay exists. Because of this it is ill advised to kill Infestors at close/melee range on Nightmare. Back away when they are at low health, as the combination of creep, charge, and instant spawning makes Parasites almost impossible to avoid.

Spawn Creep
On higher difficulties, Infestors will spawn patches of creep when they die, greatly increasing the speed of Parasites and infested hordes. In Nightmare Mode, the creep will remain permanently.

Cliff Walk
Infestors slimy exterior gives them enough traction and suction to allow them to scale most surfaces. This can be problematic as it essentially allows them to move in and out of Apollo at will. However, players will quickly learn the chokepoints and can use this to aid them in tracking Infestors.

Burrow
Infestors will not have this ability on Recruit Mode. The Infestor will attempt to flee when severely injured by burrowing, them moving away at high speeds. It can however, still be Knifed, both slowing it, and providing a blood splatter to chase. Adding points into Perception, or using a Thermal Sight will also help in chasing burrowed Infestors.

Lay Eggs
Infestors will not have this ability on Recruit Mode. When the Infestor has been agitated, it will change colors, indicating its aggressive state. When it glows bright yellow it is about to lay a clutch of several eggs. Infestors will often lay eggs while burrowed as it flees. The Infestor will typically lay around 1 egg for each player. These eggs will hatch into a combination of Blindlings and Banelings. This can be especially lethal if the team was not alerted to the Infestor beforehand. If an Infestor escapes and lays egg, A pack of Banelings and Blindling can quickly kill almost any player should they ambush him around a blind corner or sight blocker.

Detector
Infestors can detect cloaked units within 5 radius.