I just read a book called the cylcle of fire by janny wurts it is actuall three books in one. It is really good and i suggest it. i think it is out of print though so try and find if you want to its a good fantasy wizard book with demon and some twists that are interesting
it is about a wizard that is taken away under a crime he did not commit, he entrusts a little girl with a magical feather thats just the what happens in the first chapter it gets quite complicated but it is really good. basically they are trying to defeat the demons