The Hob's Bargain by Patricia Briggs

Aren has finally shed her spinsterhood by marrying a much younger man, Daryn, When she sees a vision of disaster in the near future, but because mages are either enslaved by the powerful blood mages, or put to death - and definitely frowned upon by the normal villagers, she makes a bad decision not to warn him. When bandits come and kill him and the rest of her family as they work the fields later that day, she is able to hide in the cellar until they have finished ransacking the house. When the villagers arrive bearing the body of her husband, she decides to "out" herself to deliver a warning about what is coming.

At the same time as the bandit attack, there is also "a disturbance in The Force", where all sorts of magical bindings are dispelled, and huge earthquakes cause mountains to collapse, blocking most of the roads out of the village.

I've seen this plot beginning before, in one variation or another...bereft young woman leaves home and family, or loses home and family, to venture out into the wide world to discover her gifts, from Fawn in Bujold's Sharing Knife series to Paksennarion in Moon's chronicles.

The problem with this story is that it is painfully slow starting, with a mostly pointless scene where the Fallbrook village elders yammer and decide nothing and pages of Aren cowering in the basement dealing with her grief for a week. Eventually she sets of with Kith, a crippled ex-soldier, and Wandel, the harper on an expedition towards the mountain called The Hob, trying find out if there are any survivors from the next village over, Auberg, which was flooded after the earthquake blocked the river flowing through the valley.

Regular fantasy readers can probably figure out that, given the title of the book and the logic of magic realms, there is actually a hob on The Hob, and our intrepid heroine is likely to make a bargain with him. When Fallbrook is on the verge of being overrun by the bandits at last, Aren makes a solo trip to the mountain and brings back the hob who dwells there (the mountain is sentient, by the way) to help the villagers in their struggle. Of course, bargaining with a hob may be a bit like dealing with the devil, so...

The pace continues to be slow, as the villagers and the bandits have minor skirmishes, and the hob, CaerFaun, teaches Aren steadily how to use her magical abilities, which not only are good for visions, but allow her to communicate with the recently released spirits and other magic creatures, and control some of them to an extent. In the long haul, the Hob's Bargain turns out to be a win-win-win situation, for the hob, the villagers, and for Aren herself.