Wizard of the Grove — Tanya Huff

In the age of gods--dwarfs, centaurs, and other Elder Races roamed the lands freely, and the race of mortals was created as a mere plaything for Lord Death.
 
In the age of wizards--the power games of these immortal children of gods went too far, and so the dragons flew to bring wizards down in flames.
 
In the age of mortals--the Elder Races have withdrawn almost completely from the world of humans. But one wizard still survives, a master of evil bent upon domination. No mere mortal can stand against him, so the Elder Races have chosen to intervene one final time. Their gift is Crystal, the Child of the Grove, the last-born wizard who will ever walk the world. And thus the final battle is about to begin....