Q: I used to have an old miniature named Suul the lich. Who was Suul?
A: To find Suul, one must venture deep within Undermountain. Specifically, to room #54 in the Ed Greenwood’s 1st edition The Ruins of Undermountain boxed set:
"The hallway ends here in a single broad stone step leading up to double doors of gleaming, polished bronze. An eerie green radiance emanates from this step, illuminating the doors above. Set into each door is a human skull. Two massive pull-rings dangle from the outward-opening doors."
Beyond these doors waits Suul, who “achieved lichdom through a procedure of his own devising,” which resulted in all the conventional powers and immunities of a lich, the spellcasting abilities of a 20th level wizard, as well as immunity to fire, magic missiles and illusions (plus all magic that aimed to deceive the senses), the power to fly, and the power to detect invisibility.
"Atop the column is a large open book, and a skeletal figure in tattered, rotting robes stands there reading, concurrently smoking a long clay pipe."
Suul exists to collect further spells for his major spell book (which contains nearly every known common spell, plus several of his own creation—literally “any spells the DM cares to place within its bindings”). For such a powerful item, DMs are advised that: “If PCs gain this powerful tome, it is suggested that thieves, minor mages, and other creatures be able to somehow know of its presence (perhaps the book contains a beckoning curse), and make repeated attempts to steal it or take it by force.”