You can only enter this dungeon after speaking with Mage Syltyn Rillon. Syltyn is located just outside of Glenden Wood at 27.8N, 24.7E.
This dungeon contains a maze of portals that be confusing to navigate without the use of a guide. A Tale of Paths uses a story as a guide for using the portals, the book is given to you by Mage Syltyn Rillon and is also found in front of the initial two portals. The west portal follows Atlas' route and the east portal is Syretta's route from the story.