The Scarecrow by Kailin Gow

Parker James killed his father, one of the founders and kingpins in the Inner Circle.
Now his son, groomed to replace the father in the Inner Circle, and trained to be an assassin will seek revenge.
He is known as the Scare Crow.
Perfect for Parker James. Having the Scare Crow after him will get him closer to Oz.
But now the other players, including Dorothy, The Wizard, and the Lion’s coming out to play, too.