A Race Against Time

Premise:
It was the end of the world. A stray planet would destroy everything that was and could be. As the planet threatens to destroy Earth, time portals pop up in different settlements; allowing survivors to go back to different periods in time.

Petra Stonecrest was one of those survivors. She was born and raised in an advanced civilization with the peak of human technology. Yet she was forced to go thousands of years back, in a world so unlike her own.

Her beloved Morrigan was left behind and she struggles with grief, as she desperately learns the art of time-travel in hopes of saving her.

Will Petra succeed or not? Or will she perhaps achieve something even greater?

(Note: I know this seems more like sci-fi and stuff but it's fantasy so don't be surprised lol)