Academ's Fury is the second book in the Codex Alera series written by Jim Butcher.
And what really sets this book apart is Jim's “magic system” which, without giving too much away, involves elementals bonding with humans and working with them. This sets a base for some really amazing action sequences, including well planned sieges and defenses that are rarely done well in novels.
To top this all off the characters have been given interesting personalities, and you will find yourself wanting to discover what happens to each one as the story progresses.
All in all, this is a book in a series that is un-put-downable, with plots twists and engaging language that will keep your eyes glued to the page.