The Ideal Masters are mysterious, ancient, arcane entities, apparently sentient, who rule over the plane of Oblivion known as the Soul Cairn. It is neither known how many of these beings exist, what form they take (or may take) nor has their origin been determined. They are known only to exist in the Soul Cairn, although they are known for certain to take an interest in the events of the mundane world and can observe events there.
The Ideal Masters are known to indulge the occasional aspiring Necromancer, offering him or her deeper arcane knowledge and greater power while ultimately leading them to doom and enslavement in the Soul Cairn.
One such Necromancer was the Dragon Durnehviir, who was tricked by the Ideal Masters and forever enslaved by them as a great guardian of the Soul Cairn.