It was placed here because the directors originally planned to release Left 4 Dead exclusive DLC maps that featured the Cabin In The Woods' cabin as well as the underground facility. This idea was eventually scrapped when the company producing the DLC went bankrupt.
Physical Description and Attributes
The Charger is tall, bulky man that has been horribly mutated over time due to an unknown zombie-like virus. He wears a pair of blue overalls, and only wears one shoe on his left foot. It appears the Charger's head has either suffered a severe impact of some sort and his cranial is caved-in. He has sunken, white eyes, and his nose appears to have been bitten or torn off, as there is a large amount of blood spewing and dripping from his visible nasal cavity. His mouth is also disfigured and he is missing some teeth.
The most notable features of the Charger are his arms; his right arm has been severely mutated and has experienced intense muscle growth to the point of the skin tearing and rotting away. His left arm is extremely frail and skinny, and looks as if it has been destroyed by gangrene or by the very virus that has infected him.
A vile of Boomer Bile is what could possibly summon the Charger.
The outline of a Charger is seen in the movie during the elevator scene, in its cube near to top left. It is not seen during the System Purge.