Little is known about the origins of the art or when it died out. It is speculated that some knowledge of it has lingered over Tamriel and it has been used on several occasions (Henantier's Dream Amulet is believed to have used this magic).
The art was rediscovered by, the witch, Agatha Tira, who discovered several books on the subject and grew fascinated by it. The Breton dedicated several months to writing a book about it, hoping to observe or even invade people's dreams. She wrote the book, whilst exploring Mehrunes Dagon's plane of Oblivion.
The book was completed and found by The Companionship in The Legend of Nirn. It apparently described the theory behind it but nothing practical about learning the ability.
There are only two known Dream Walkers in Tamriel, Agatha Tira and, the vampire, Dunlammus. Tyranil, a shadow mage, who sought to destroy the Thalmor and rule Nirn also had an interest in the art but he didn't have the resources to study it.
Levels of Ability
Dream Walking takes many years of study to master, hence why few humans practice it. The extent of a Dream Walker's power depends on how long they have studied or practiced the art.
Novice: A novice Dream Walker can observe a dream as the dreamer sees it. They cannot intervene or interact with anything in the dream. It takes approximately ten years to become a novice.
Apprentice: An Apprentice Dream Walker can observe a dream from more than one perspective, they can walk around a dream, freely and observe it from any angle but they cannot intervene or interact with anything in the dream. It takes approximately twenty five years to become and apprentice.
Adept: An Adept Dream Walker can interact with the dreamer, appearing to them and communicating with them. They cannot intervene or interact with the dream in any other way, just the dreamer. It takes approximately fifty years to become an Adept Dream Walker.
Corrira Thromius is an Adept Dream Walker in the Order of the Dragonblood.
Expert: An Expert Dream Walker can interact with the dream and the dreamer. They are able to pick up and move objects, inflict minor damage on the dreamer and teleport object through dreams. They cannot manipulate the dream itself, the environment cannot be changed nor can the dreamer's illusions. It takes seventy five years to become and Expert Dream Walker.
Agatha and Dunlammus are both expert Dream Walkers in The Legend of Nirn.
Master: A Master Dream Walker can manipulate a dream, creating illusions and reshaping the world around the dreamer. A Master in Dream Walking can kill a dreamer in their sleep. They can manipulate and teleport objects to/from a dreamer, with little to no difficulty. It takes approximately one hundred years to become a Master Dream Walker.
Sigard, while posessed, is a Master Dream Walker in Legend of Nirn: World of Ruin.
Agatha Tira is a Master Dream Walker in Aubeanic Reign.
Augur is a Master Dream Walker in The Order of the Dragonblood.
Lilina appears to be a Master Dream Walker, though her abilities could ascend Agatha, Aratius or Augur's.
- The Order of the Dragonblood