The Phoenix Unchained by James Mallory, Mercedes Lackey (2007, Hardcover)

If you like Mercedes Lackey, this is another great series. It follows on an earlier series, but you can read this one without that one as well. I actually ended up buying this book twice because I couldn't remember the title (story has nothing to do with a phoenix... I assume it just is a reference to the rebirth of a certain type of magic).