Flesh and Fire

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.

Synopsis from Open Library.