Flesh and Fire: Laura Anne Gilman
Back cover:
Once, all power in the Vin Lands was held by the prince-mages, who alone could craft spellwines, and selfishly used them to increase their own wealth and influence. But their abuse of power caused a demigod to break the Vine, shattering the power of the mages. Now, fourteen centuries later, it is the humble Vinearts who hold the secret of crafting spells from wines, the source of magic, and they are prohibited from holding power.
But now rumors come of a new darkness rising in the vineyards. Strange, terrifying creatures, sudden plagues, and mysterious disappearances threaten the land. Only one Vineart senses the danger, and he has only one weapon to use against it: a young slave. His name is Jerzy, and his origins are unknown, even to him. Yet his uncanny sense of the Vinearts' craft offers a hint of greater magics within magics that his Master, the Vineart Malech, must cultivate and grow. But time is running out. If Malech cannot teach his new apprentice the secrets of the spellwines, and if Jerzy cannot master his own untapped powers, the Vin Lands shall surely be destroyed.
In Flesh and Fire, first in a spellbinding new trilogy, Laura Anne Gilman conjures a story as powerful as magic itself, as intoxicating as the finest of wines, and as timeless as the greatest legends ever told.
Jerzy, raised from his status of slave, becomes the apprentice of Malech unexpectedly. Like all his kind, Malech, a Vineart, can coax from wine true magic. Wines imbued with magic, called spellwines, can be used by anyone to do things like set and heal bones, create light without burning, or influence weather. However, the realm of temporal power is permanently blocked off for Vinearts--they are forbidden to do so by Sin Washer, a Jesus-like figure who broke the power of prince-mages a thousand years ago by blooding the grapes and is still worshipped today.
But things are not right--from all corners come news of petty plagues and harvest problems, sea-serpents attacking villages, and an entire island disappearing. In the isolated Valle of Ivy, where Vineart Malech has his vinyards, Jerzy studies at a frenetic pace. Hearing the news all together forms a disturbing picture, and Malech is concerned. Against all tradition, he sends Jerzy to another Vineart to try to understand what is happening, though Jerzy has hardly been a year under his tutelage.
This is an excellent book that I would definitely recommend--I really enjoyed the worldbuilding and the characters. There's a somewhat more spoilery review on my journal that talks more about it!