The Blackest Flame — R. Peter Ubtrent

Aurora has changed time. And not just a little bit. She's completely changed everything in The Land of the Five Rivers. It's not even called that anymore and the worst part is that no one she knew before, exists. Man is the dominant species and the half-creatures and were-creatures have been herded into an area out of which they are not allowed to travel on penalty of death. Aurora is now faced with trying to figure out what she did and how she can fix it but the problem is that magic doesn't exist here in this new land. She's the only one with magical abilities and no way to re-charge her powers. When she senses that someone else has magic, although faint to be sure, she starts on a journey to find them and perhaps they can explain what she did wrong this time....