Hollow (Book 1 in the Crown of Hearts & Chaos series)

It was impossible in the way all magic was impossible, but water sprites and bargaining Hags were nothing in comparison to this. The magic here was ancient, sentient and hauntingly intimidating. And in the six hundred and fifty years since the curse began, there was barely a single year missed. Raven, Boar, Serpent, Unicorn and finally the Dragon itself.