The Master

An illithid who dwelled deep under the Four Towers of the island of Nidan in the Chibouholm Isles, and who, possibly due to the presence of The Legion of Llandos, succeeded in awakening his master, the Sleeping Eye. It and the beholder clashed with the Legion, but they escaped with Hachoo.

The Legion encountered the Master and the Eye again in an ancient illithid complex in the Mushroom Forest region of the Underdark and managed to slay it, though the Eye escaped with its body.

As it happens, The Master was not dead. Later it became the chief mastermind behind The Black Chorus, almost successfully orchestrating the downfall of the Legion (and succeeding in killing Camarion Llandos VII), but Ember caught him in the Bag of Capturing.

It was later discovered that he had somehow escaped from the Bag.

Sometime later, he was behind a plot to awaken a lich and conquer Sablos with an army of undead, which almost succeeded, but for the Knights of Sablos and the Legion. He was taken alive and imprisoned in the dungeon of King Oriel.

Years later he escaped again and disappeared from Jesenreth.