It was placed here because the directors originally planned to release Left 4 Dead exclusive DLC maps that featured the Cabin and the Facility. This idea was eventually scrapped when the company producing the DLC went bankrupt
Physical Description and Attributes
The Witch appears as a middle aged woman who has been severely mutated due to the Green Flu outbreak. As a result, she has suffered several physical as well as psychological changes as her infection mutated over time. The Witch, as both seen in the film and in Left 4 Dead itself appears slumped over on the ground, sobbing. Her wails are very loud and alert people of her presence. The Witch's skin is a pale grey color. She wears a tattered, pale tanish-grey bra with matching bottoms. Her hair is long and is a shiny silver color. The Witch's most notable features are her claws; it appears that her fingers have grown into her nails, extending their length into strong and sharp claws she uses to attack her victims with.
Its possible that a vile of Boomer Bile is what summons the Witch to the Cabin. However, in the Left 4 Dead game, the Witch is notably attracted to sugar, so its possible this could also summon her as well.