I'm looking for a book I read about 10 years ago.
Unfortunately, I don't know how old the book was at the time. It was borrowed from a library so the state of the book is a very bad indicator, that being said I am certain that is was not brand new at the time. Could be anything from 2 to 10 years older [ca. 1998-2006].
The target audience is probably young-adult, but I wouldn't classify it as a typical one at that.
I can't remember much from the book, but there are 4 guardians and a master living in the capital. Their job is to keep the world in balance. I think this is ruined by a woman who kills the guardians and seduces the master.
The only other thing I remember is that the protagonist learns to use his magic while raking leaves because the color of them reminds him of fire, he then accidentally sets the pile of leaves on fire.