The books Dealings with the Territory of Mayene, 500 to 700 of the New Era and Treasures of the Stone describe the doorways. The twisted redstone doorframes are a pair of ter'angreal of polished redstone. One doorway has with three lines of triangles points down along each upright, the other has three sinuous lines running down each upright from top to bottom. These symbols allow the user to discern which inhabitants on the other side of the door they will interact with. The doorways look twisted and cause one's eyes to slip away before being able to tell as to how it connects at the top. Any person can step through the doorway, since channeling is not required, but they can use the ter'angreal only once. When the person steps through, they experience white light accompanied by a vast roar of sound. One is located in Tear, the other was discovered in Rhuidean.
The doorways provide protected access to the world of the Aelfinn and Eelfinn, parallel world of the Finn. The Tower of Ghenjei in Andor can be entered by applying the rhyme from Snakes and Foxes, but this approach gives the entrant no protection from the wiles of the 'finn. Aside from entering the Tower directly, they are the only known intersections between the human world and the Sindhol.
In this ter'angreal the user and the 'finn are bound to an agreement. The petitioner can ask three requests from the Eelfinn or three questions from the Aelfinn and the 'finn will always grant them... at a very high price. As well as the price, the 'finn savor the petitioner's experiences and emotions and forge a mental link so they can harvest their experiences and memories when the petitioner returns to their own world. The petitioner must also abide by the treaties and agreements and carry no iron, instruments of music, or devices for making light.
The Aelfinn doorwayEdit
Aes Sedai studied the twisted red doorway for years when it was owned by Mayene. Three hundred years ago Halvar, the First of Mayene, traded it to Tear and it was entombed in the Great Holding of the Stone of Tear. Mat Cauthon, Rand al'Thor, and Moiraine Damodred all use this doorway at the same time. After finding Moiraine, Mat and the others make their way to the original room where Mat entered the realm of the Aelfinn. The twisted red doorway is shattered with nothing but chunks of red rock rubble left. It can be suggested that the doorway was somehow destroyed by Moridin when he came to kill Lanfear, held captive by the Finn.