Karsus Lord Karsus was the Netherese creator and caster of the " Karsus ' s avatar " spell that triggered the Fall of Netheril . History . Early life . Karsus was born about 3 , 100 years after the nation ' s founding , in - 696 DR . He was able to cast his first spell at the age of two , and by the age of twenty - two had become the youngest arcanist to ever create his own floating city . Gifted with magic , but lacking the necessary discipline that comes with hard work and research , he founded a school of magic on his enclave and encouraged the attendance of radical thinkers and those interested in taboo projects . One of his students , now known only as Lord Shadow , wrote a treatise on the exploration and exploitation of other planes , such as the Plane of Shadow , which garnered initial criticism but was eventually embraced as the key to an infinite source of shadow - creatures as slave laborers as well as a dumping ground for unwanted garbage . Creation of " Karsus ' s avatar " . In - 345 DR , Arthindol the Terraseer appeared before Karsus and stated , " Mystryl was about to face her greatest challenge - one that could alter the perception of magic for all time . " Shouldering the responsibility for preserving his civilization , Karsus finished creating a spell , " Karsus ' s avatar " he had been developing for years . This spell would steal the power of a deity and transfer it to the archwizard that cast it . Karsus believed that with the power of a deity at his disposal , he could destroy the Phaerimm and unite his people . Karsus cast the spell in the 3 , 520th year of Netheril , - 339 DR , and chose Mystryl , the goddess of magic , as his target , feeling that she was the most powerful deity and the most appropriate choice for his purposes . Karsus gained the powers over all magic . Fall of Netheril . Unfortunately , his choice was a terrible mistake , for one of the responsibilities of the deity of magic was to regulate the flow of magic to and from all beings , spells , and magic items in the world . Lacking the ability to do so properly , magic surged and fluctuated . With her last remaining bit of power , Mystryl sacrificed herself to block Karsus ' s access to the weave , causing all magic to fail . The flying cities of Netheril plummeted to the earth . The severing of the link also killed Karsus and transformed him into stone , and the last thing he saw was his entire civilization being destroyed because of his actions . This was to be known as Karsus ' s Folly . The stone form of Karsus eventually landed in a part of the High Forest , now called the Dire Wood . The city of Karse was built around its base . Final fate . Karsus was never accepted as a petitioner by any god , nor did he go to the Fugue Plane when he died . Instead , his soul was bound to the Material Plane . Those with experience in Pact magic can call up his vestige where he appears as a giant blood red boulder , like the one found in the High Forest where his petrified form landed . Blood burbles up from the top of the stone , trickling down the side facing the summoner , pooling at the base . When he speaks , the pool fountains upwards , its height varying on the volume of his voice . Karsus grants the summoner a boost in magical ability , though he also imparts some of the arrogance he is reknowned for . Also , this vestige for some reason has a strange enmity toward Amon . Legacy . Karsus held a small cult of worshipers who venerated the ' momentary god ' . They were mostly based at Karse until its abandonment . Exposure to heavy magic and Karsus ' own proximity also led to the creation of the karsite s , a race of people born with an inherent distrust of magic as well as a natural resistance to it . Appearances . In the game " " the hero meets Karsus in a hell created by a book in the Great Library of the risen Netherese city of Undrentide , which is implied to be Karsus ' s own city . Karsus was being tormented by devil s but the player can choose to be redeem him by re - writing the magical tome in which his spirit is imprisoned . Doing so will ensure that Karsus is present to assist during the battle in the Library ' s final magical tome .