The Special Infected are the mutated variants of Common Infected. Through some unknown mechanism of the Green Flu, a small percentage of Infected humans will undergo a dramatic mutation, eventually turning into one of these Special Infected, each with their own unique inhuman abilities. They don’t spawn as regularly as the Common Infected do, but their abilities can easily wipe out a team ofSurvivors if you don’t deal with them quickly, making them the true teamwork testers of the Left 4 Deadgames.
Four of these Special Infected (namely the Hunter, Smoker, Charger, and Jockey) are “pinners”, as when they attack you, they “pin” you, requiring another Survivor to knock them off (or in the Charger’s case, kill them) for the trapped Survivor to be free from certain death. The other two Special Infected (theBoomer and the Spitter) act as support for the pinning Infected, as their attacks can help slow down the Survivors enough for a pinning Infected to attack them. The final two Special Infected (the Tank and the Witch) are considered to be “Boss Infected”, as they have a very high amount of health, they spawn at the rarest rates (sometimes at fixed points), and they can easily kill a Survivor in a matter of seconds.
The Special Infected have higher intelligence than the Common Infected, shown throughout the whole game. Special Infected are not affected by the beeping sounds of the Pipe Bomb. They will bide their time, waiting for Survivors to reach “ambush” areas before attacking them sometimes. Several Special Infected, like the Boomer, Spitter and Smoker may also hide after attacking/attempting to attack a Survivor.
The Director can decide what Special Infected it should spawn to combat the Survivors progress through the levels. It can spawn any Special Infected, although it will look at the team’s progress; if they do fairly well, it will spawn more threatening Special Infected while if they do poorly, will spawn Special Infected that can be easily countered. The Director will usually spawn one or two Special Infected at a time, only spawning more then that during Finales and panic/crescendo events. The Director will also be unable to spawn that Special Infected once it spawns, apart from special circumstances; for example, in most situations, it can only send one Tank at a time, apart from The Plantation and The Port finales, where it can summon two or three at the team.
Special Infected have a cap of 4 present on the map at any time in a normal game (e.g Single Player). If playing on Mutations, it will greatly affect the Director’s ability on spawning Special Infected; for example, playing on the mutation “Hard Eight” allows the Director to double the spawn cap (up 8 Special Infected present at any time on the map).