They are an enigma to the inhabitants of Tamriel, and only those who make deals with them or have visited the Soul Cairn know of their existence. Most individuals who deal with the Masters are deceived, and subsequently their souls are condemned to the Soul Cairn. While there are theories, exactly why the Ideal Masters crave souls is unknown.
It has been speculated that the Ideal Masters have transcended beyond physical manifestation and now exist as non-corporeal beings. When they do interact with others, be it to feed on their victims or speak to their underlings, they do so through the crystalline structures that dot the Soul Cairn.
The Ideal Masters' weakness is their hunger for pure souls. This hunger is believed to be the reason for the existence for the Soul Cairn itself, and it is often the only leverage necromancers have when bargaining with them. In return, the Ideal Masters grant them the ability to conjure powerful undead guardians in a similar manner that conjurers would summon an Atronach or Daedra.
In An Elder Scrolls Legend: Battlespire, the player will speak to the Ideal Masters as part of the Soul Cairn questline. Since the Daedric armies of Mehrunes Dagon invaded the Soul Cairn, the Ideal Masters needed assistance in ridding the Soul Cairn of the Daedra. The Daedra planned to use it as a waystation between their own realms and their newly conquered domains. The Daedra killed the Masters' servants and plundered their treasure, although they also released the souls of several prominent mortal allies whom Dagon had betrayed into the realm. An apprentice battlemage from the Battlespire entered the realm, following the retreating army. Most of the Ideal Masters are unwilling to help the player, but when they learned of the Daedric invaders who would supposedly continue to regularly pass through their realm, one Master instructs the player on how to use the Emerald Gates to leave the realm and continue stalking Dagon's army. The gates can then be used to travel to the Shade Perilous.
At some point in history, a dragon named Durnehviir turned to necromancy to gain an advantage over his rivals. He was granted the power to accomplish feats such as summoning legions of undead. In exchange for this power, the Masters tasked him with guarding the Soul Cairn until a powerful necromancer named Valerica, who was imprisoned there, died. Durnehviir accepted, but he did not know that Valerica was a vampire and therefore immortal. As result, Durnehviir was doomed to guard the Soul Cairn for eternity.
- Shard of the Ideal Masters can be found in The Elder Scrolls Online.
- The Ideal Masters were once mortals and formed an early order of sorcerers who practiced necromancy, trafficking in souls, great, small, and fragmentary. They became very powerful, and eventually found their physical forms to be unacceptably weak and limiting. They transcended those forms and became beings of soul-energy.
- An Elder Scrolls Legend: Battlespire
- The Elder Scrolls V: Dawnguard
- The Elder Scrolls Online (mentioned only)