Dhiammara by Maggie Furey
Aurian faces bitter defeat. She has failed to master the Sword of Flame, her only defence against the forces of evil. But she has also unleashed the deadly, unpredictable Phaerie upon the world, and the end of that is unknowable. And now she must journey through time itself...Eliseth, the coldly ambitious Mage who has been Aurian's nemesis since her first days in Nexis, has captured both the Sword of Flame and Anvar, Aurian's soulmate. Now, Aurian and a few allies travel into an uncertain future. Knowing she must defeat Eliseth, who controls the Cauldron of Rebirth, without destroying the world, Aurian is faced by many dilemmas before she finally reaches the ancient Dragon City of Dhiammara. There, in the home of the extinct fire lizards, a final conflict will take place, in which Aurian must triumph or die.