The Outstretched Shadow by Mercedes Lackey and James Mallory is book one of The Obsidian Trilogy. It is followed by To Light a Candle and When Darkness Falls.
This first book in the trilogy starts out very promising. Unfortunately, the initial plot which I found quite riveting begins to slow and finally fall flat for me as I gave up reading about halfway through.
Kellen Tavadon, son of the most powerful mage in the Golden City, wants more out of life than the controlled, sanitized life given to him by his father and the other ruling mages of the City. He finds more than he bargained for when he happens upon the three books of Wild Magic.
Wild Magic differs from the traditional magic performed by the City's mages in that it is easier, requires less preparation, is in some ways more powerful, but ultimately was banned long ago by the mages of the Golden City because it exacts a price that is sometimes too high to pay. Kellen soon learns there is even more to it than that when he is discovered practicing this forbidden magic and banished from the City and its utopian way of life. This is all well and fine with Kellen. Others have been expelled from the city and, he imagines, gone on to lead a new, independent existence free from the stifling rules of the mages. He comes to find out, though, that of those previously banished, none still live, for the mages set an Outlaw Hunt in pursuit of him: a pack of stone golem hounds whose only purpose is to kill those expelled from the City.
This is a great premise and the story does well up until the point where Kellen settles into a life free from his father's influence. He begins to delve further into Wild Magic, albeit slowly, and discovers there is an entire world of fascinating people living outside the borders of the City. The problem is that the story settles far too much into the mundane. Meeting new neighbors, attending fairs, chopping wood, observing Kellen's sister, who is a healer, going about her daily routine. In a way, I found the manner in which Kellen settles in with his sister to be a bit… unwholesome; I think the sister character's part would have been better served as a non-blood relation.
I read some reviews on the second book in the series, To Light A Candle. Those reviews claim the second book picks up the pace. Unfortunately, I couldn't make it to the end of The Outstretched Shadow, so I won't be getting to see that for myself.