Uprooted - Naomi Novik

A Dark Enchantment Blights the land. Agnieszka loves her village, set deep in a peaceful valley. But the nearby enchanted forest casts a shadow over her home. Many have been lost to the Wood and none return unchanged. The villagers depend on an ageless wizard, the Dragon, to protect them from the forest's dark magic. However, his help comes at a terrible price. One young village woman must serve him for ten years, leaving all they value behind. Agnieszka fears her dearest friend Kasia will be picked at the next choosing, for she's everything Agnieszka is not - beautiful, graceful and brave. Yet when the Dragon comes, it's not Kasia he takes.