Frostwing by Richard A. Knaak

Grigori Nicolau thought that he could escape the gargoyle haunting him for centuries . . . only to discover that the creature called Frostwing was the least of his dangers. From the best-selling author of the Dragonrealm comes the shadowy fantasy of Grigori Nicolau, a wizard whose dreams have been haunted for centuries by the malevolent gargoyle he calls Frostwing. With each visit, the gargoyle steals a random memory from Grigori, leaving deep holes in his mind that will someday betray him. Now, in modern Chicago, Grigori must confront an adversary with more knowledge of his past than he himself, and he must discover the secret behind the sinister web spun by a sorcerer dead long, long ago . . . a web designed specifically for Grigori Nicolau.