Guild of Illusionists
The Guild of Illusions was one of the minor guilds of D'ni. The guild was in fact an illusion itself. It was created as a public front for a secret police sort of organization known as the Relyimah (The Unseen).
During the reign of King Yableshan, a mole infiltrated the Relyimah, preventing them from being successful in several investigations, including the kidnapping of the King's son. In response, the King placed a man named Faresh in charge of the guild (and thus, the Relyimah) in 5043 DE, with the sole task of uncovering the mole. After the death of his daughter, Faresh left the Guild, donating his mansion on Katha island to them (and thus the Relyimah) as a headquarters.
The Relyimah organization met with an unfortunate end under the reign of King Lanaren, when he divulged the existence of the organization to the public. It is unclear if the Guild of Illusionists was also dissolved at that time.