The Shadow Labyrinth — Thomas K. Carpenter

A new danger looms on the horizon as a murderous horde of warriors plan to invade the continent. With throngs of enemies approaching their shores, Terran must locate a black crystal and become the game's most powerful Crystal Bard if he has any hope of defending the Mother Tree and the denizens of Belwar. But the only known crystal is guarded by a creature whose awakening could threaten the entire world, leaving him with an impossible choice.