Window In Time: a time-travel fantasy

The Obsidian Star, a magickal spellbook (grimoire) capable of granting enormous dark Power to the wizard who lays claim, has been a closely guarded secret of the wizard Grand Council for centuries. When Warlock Hunter Sloane learns of its existence he storms the Merlyn Academy, killing all who stand in his way of claiming the Star.
Sentinel Sebastian Darkus embarks on a quest to reverse these events by traveling back to before the warlock has learned of the grimoire in order to destroy it. When he meets Kenna, his future wife, three years ahead of schedule, subtle alterations in the past began occurring. Past and Future are merging as the timeline shifts.
Before Sebastian can figure out the cause, he and Kenna are forced to run for their lives. Their escape takes them on a twisted path from 2009 San Francisco to MistyShadows, a magickal realm abutting their own, to 2012 San Francisco, and to the 16th century to seek out the Enchanter of Camelot—Merlyn.