WarCraft. War of the ancients trilogy

The young druid, Malfurion Stormrage, leads the night elf defenders alongside the wizard, Krasus, to battle against the Legion, but in their darkest hour the dragons rise, bringing with them a powerful artifact--the Dragon Soul--which can drive the Legion from the world.

Months after the cataclysmic Battle of Mount Hyjal, a mysterious energy rift within the mountains propels three former warriors into the distant past, where they must defeat the Dark Titan or risk creating an Age of Darkness that will engulf the world.