Forgotten Realms Curse of the Shadowmage The Harpers #11 Mark Anthony TSR 1995
Long ago, the shadow magic transformed an ancient wizard into a being of utter evil, the Shadowking.
Now legendary Harper Caledan Caldorien, heir to the shadow magic, has mysteriously vanished. The Harpers mount a mission to find and destroy.... Caledan.
But renegade Harper Mari Al-maren and the mage Morhion embark on a desperate quest to rescue him, and stop Caledan before the Shadowking stalks the Realms once more!