Until comparatively recently, Dwimmermount remained sealed to the outside world, as it had been since the fall of the Thulian Empire. That didn't stop many from attempting to find a way into the fabled mountain fortress in order to loot its treasure troves and gain access to its storehouses of magical secrets.
Much attention was focused on the so-called "Alchemist's Door," an archway decorated with alchemical symbols and placed against a low wall along the Path of Mavors, the ancient Thulian stairway winding up the face of the mountain. The Alchemist's Door wasn't the only archway to be found along the Path, but it was the only one marked with arcane runes and sigils, leading some to believe it must be more than a mere ornament.
Unfortunately, no evidence for this assertion could ever be uncovered. All attempts to open the "door" supposedly found inside the archway have proven fruitless. If there is a door or portal to be found here, its method of activation remains unknown to even the most knowledgeable of sages.
The Truth: The Alchemist's Door is a means of entering Dwimmermount but it requires both a Triple Conjunction of Kythirea, Areon, and Ioun (which occurs only once every 58 years) and a quantity of liquefied moon argent (12 drams), an extraterrestrial metal rare since the fall of Thule and the end of regular commerce with Ioun. The liquid metal must be used to outline the Door during the Conjunction, which creates a temporary dimension door leading to Level 3A: The House of Portals. Once the Conjunction ceases, the Door closes and cannot be opened again by any means until the next Conjunction.