Trapped in Time — Clifford B. Bowyer

The plan had been a simple one: use the Shard of Time, a mystical artifact that transports the user to any destination in time they wish to go, to learn more about Kyria's arch nemesis, Zoldex. The plan went awry. Now, Kyria, along with her best friends, Mica and Sartir, find themselves stranded thousands of years in the past, in a realm that is overrun by tyrants, war wizards, and evil sorcerers. It is a time before the dawn of Mages, and nothing that they had learned at the Mage Academy could possibly have prepared them for this. Their only hope: to survive long enough to find the Shard of Time where it had originally been discovered, and use it to bring them safely home. On their journey, they shall learn that for a trio of children, even Mages, that the past was a dangerous place to be, and the chances for success is minimal.