The Eye in the Stone — Allen L. Wold

DEMON WARS...

Twentieth-century sorcerer Morgan Scott was pledged to fight they Servants of evil wherever he encountered them. He never expected to find them in the small town of Harborbeach, Michigan.

But when he arrived there on a long-overdue visit to his brother Michael, Morgan found his brother had vanished, claimed by the Servants for some horrifying doom. Seeking to find and rescue Michael before it's too late, Morgan and his familiar, the dragon cat Phoebus, begin their quest for a legendary relic of dark magic!