The Evil Forest was seen in the episode "Tree Trunks," where Tree Trunks wanted to go to this place to find the Crystal Gem Apple. The forest is filled with many evil creatures and is considered very dangerous, which is why Finn didn't want Tree Trunks to go alone.
Appearance[]
The forest is very thick, the trees are large and have a black color. Oddly, the trees have holes in them that resemble mouths.