You now have the Crown of Karsus, created in his attempt to usurp Mystryl as the new God of Magic. Despite the eventual failure of Karsus, for a brief moment, he achieved his goal of apotheosis. Implanted in this crown is the portion of the weave that Karsus stole.
Just being near the crown boosts those with the gift of magic, towering them in magic power that would put them near the realm of Karsus in the system of magic that they wield. Long-term exposure from wearing the crown would eventually see you gain power similar to the divine wielding of the domain of magic held within the crown unto oneself, becoming natural to the user and slowly allowing the user to evolve and become a true god.
However, upon the crown lie three jewels known as the Netherstones, which, when separated from the crown, allow the wielder total control over the one who wears the crown, similar to how the chosen of the Dead three control the Netherbrain.