The infinite forest refers to a seemingly endless expanse of forest in an unknown location.
The infinite forest is described as seeming to have no end, with the only gap in the expanse being a small clearing. Additionally, it was stated that no stars or other astronomical objects were visible in the night sky above the forest, instead being pitch black and empty.
In the series Edit
The forest was first seen when Mirabel Nox was transported there during her first night in Chorofeyre. Queen Titania appeared before Mirabel in the avatar of a moth and transformed her fake poppet into the Effigy of Haunting as a reward for her service, explaining how it works before transporting her back to Chorofeyre with it.