Dark Forest is a location from the 1985 animated series She-Ra: Princess of Power.
She-Ra: Princess of Power
The Dark Forest, sometimes referred to as Darkside Forest, is a region of Mystacor where many magical herbs and powders grew. For instance, powder ground from the root of the Magica Tree is well suited to make sleeping potions.
When Castaspella was dethroned and transformed into an old woman by the evil sorceress Mortella, she was banished to live in the Dark Forest and gather magical herbs for her new mistress. Mortella's Magic Knights were ordered to patrol the forest and make sure Castaspella remained in the vicinity.
Some years after Castaspella's banishment, Adora and Bow were traveling through the Dark Forest when they came upon old Casta. After helping whom they thought was just a helpless old woman, the two Rebels were captured themselves by the Magic Knights. With the help of She-Ra, Mortella was finally defeated and the rightrul rule of Mystacor returned to a rejuvinated Castaspella. As she took control, the dreary landscape as ruled by Mortella took on a more cheerful, wholesome looking state.