Fire in the Mist (Holly Lisle)

This story has all kinds of magic, and makes no pretensions of coming up with "scientific" explanations, so it works just fine! A teenager is off tending sheep when everyone in her village is killed by a plague, and her emotional response is so magically powerful the leaders of the world's magical community come searching for her. A country peasant, she doesn't fit very well into the civilized and prejudiced magical university, but they convince her she needs teaching if she's to avoid harming anyone with her untutored power. In her first weeks, a horror from the past arises and threatens to destroy everything, and of course she's the one who winds up saving the day. The story was not the greatest (the end can't square with the beginning, for one thing, and I couldn't convince myself the big schism in the magical world could have persisted as completely as it did for hundreds of years), but still enjoyable enough.