My Death Horse Overlord. The Russian Witch's Curse, #6

After being attacked during a study abroad program, Whitney Brooks decides to train in self-defense. She doesn't expect to become a sharpshooting champion. She certainly doesn't expect to be competing for the state title when the world explodes. Literally. When a massive earthquake splits a mountain open and a black horse gallops out, nostrils trailing smoke, hooves setting the scrub brush on fire, Whitney's as horrified as everyone else.
But while other weapons experts flee, Whitney feels strangely drawn to the beast. She's always had a penchant for violence. But Xolotl's on a different level. He always chooses a human when he wakes to become his champion, and Whitney's the only one who isn't screaming hysterically. In fact, he's fascinated when she tries, uselessly, to put him down. He has big plans for how he'll use her to restore balance to the world.
Because that's his job-to bring death back to the world on a large scale. Now that he's awake again, nothing can stop him. Then again, he's never met anyone like Whitney Brooks.