Oh ok. I assumed from the news releases showing a picture of a warrior pack it was going to be like the Book of Heroes 5 pack purchases. So this is just a free one to start them off or something?
It's not the Book of Heroes, but the Book of Mercenaries. The former are the stories of the original player characters, the latter the stories of the characters from the current expansion (and the next few).
I think only the Book of Heroes will come with bundles and the rest from reward tracks as the characters are tied to the expansions.