The Temptation of Elminster, by Ed Greenwood, paperback Forgotten Realms novel
“How do you tempt an archmage who has everything?
From a dark and dusty tomb, Elminster emerges, seeking the guidance of Mystra, and finds only silence. He is drawn into the clutches of the mysterious and sinister Lady of Shadows. The path he takes will lead to a Realms-shaking confrontation where Elminster has to make the most important choice of his long life.
Whatever he decides, the Realms will be forever changed . . .”