Halaster Blackcloak Halastar Blackcloak ( formerly Hilather ) was a very old and insane wizard who resided within his lair : Undermountain . History . In his youth more than a thousand years ago , Halaster Blackcloak was known as Hilather , though where he spent his youth is the source of great speculation . Some sources place him in the ancient Imaskari Empire . Whatever his nation of origin , it is known that he was more gregarious as a young man , creating and hosting magefair s and spellmoot s , and taking many apprentices . However , as his power grew , he became more interested in aberrations and the Outer Planes , which led to growing paranoia and viciousness . In 168 DR Hilather , now calling himself Halaster Blackcloak , arrived at the foot of Mount Waterdeep with his apprentices , collectively called " The Seven " . Halaster summoned demon s and other outsider s to construct Halaster ' s Hold and claimed the nearby lands as his own . Most likely he chose the location because of Sargauth Enclave , an abandoned Netherese outpost buried deep beneath the surface . Halaster refused to release the monsters and demons after they constructed his Hold , instead sending them into the caverns to explore . This began Halaster ' s Hunts , a long series of journeys into the area now called the Underhalls , driving out the drow , duergar , and various monsters that lived there . By 309 DR Halaster had complete control over the near - endless tunnels and caverns and began constructing the largest and most deadly dungeon imaginable , Undermountain . By that time , Halaster had become completely mad and wanted nothing to do with the outside world . He left his hold to live in Undermountain itself , allowing the keep to fall into ruin . Several of his apprentices came looking for him ; he slew two before demanding the rest help him fortify his dungeon even more . One refused and managed to escape . Jhesiyra Kestellharp would later become Magister and would provide what little history there is about Halaster , the Mad Mage . " Elminster in Hell " . In 1372 DR when Elminster was inadvertently sent to hell while defending the Dalelands from the Shadovar . Mystra made a bargain with Halaster , that she would try to cure his insanity if he rescued Elminster from hell . Halaster agreed , and entered Avernus . Though he was unsuccessful , and had to be rescued in turn by Alassra Silverhand , Mystra kept her word , and managed to partially cure him . ( She then proceeded to blast Asmodeus with Halaster ' s insanity . ) Halaster ' s Apprentices . Several of Halaster ' s apprentices would become extremely powerful in their own right , though all would become infected with his madness . Halaster ' s Higharvestide . On Higharvestide of the Year of the Gauntlet , 1369 DR , two members of the Twisted Rune managed to kidnap Halaster Blackcloak from inside Undermountain . The lich Priamon " Frostrune " Rakesk and the alhoon Ralayan the Ocultacle used a " ring of multiple wishes " to summon the Mad Mage to Stardock where they could scrape the secrets of Undermountain from his mind . Halaster ' s kidnapping allowed the madness of the dungeon to escape . " Gates " began randomly transporting creatures from Undermountain to places throughout the Realms , causing havoc and destruction everywhere . A group of adventurers hired by the Lords of Waterdeep managed to reach Stardock and free Halaster . The Mad Mage immediately returned to Undermountain , which quelled the chaos of the dungeon and ended the terror of Higharvestide . Halaster ' s Heirs . While the term " Halaster ' s Heirs " formerly referred to the surviving apprentices of Halaster , it currently refers to an arcanist academy on the Dungeon Level of Undermountain formed by Trobriand and Murial . Death . Shortly after dawn on Eleint 30 , 1375 DR , an earthquake struck Waterdeep . Though the city suffered little damage , many people throughout the town saw visions of Halaster screaming , his eyes ablaze with rage , sorrow , and swimming stars . Arcanists who saw the visions also reported scenes of destruction in the vast maze of Undermountain : pillars cracking and crumbling , chasms and rifts opening , and explosions of sparks . Those brave enough to investigate quickly discovered that Halaster had inadvertently killed himself while attempting a powerful ritual ; as he died , he hurled desperate visions and compulsions to people all across the continent . Personality . While in Undermountain , Halaster seems constantly distracted , always chuckling and muttering to himself over people and happenings only he can discern . He also has difficulty holding the thread of any conversation . If he is ever removed from Undermountain , he regains his lucidity . At these times , Halaster is fastidious , meticulous , and quite proper , though still thoroughly evil . Halaster can be honorable , and even noble in a way . He brooks no insolence in any case , and remembers any slight or aid given him . He also tries to get his own way in everything , caring not for the harm he does to others in the process . Blackcloak ' s interests include collecting new monsters and magic , but after thousands of years , nothing is really new to him . Whilst waiting for such delights , he amuses himself by manipulating events and politics to suit his whims . Magic Items and Spells . Over many centuries , numerous magic items and spells have been created by or attributed to Halaster Blackcloak .