One of those things than Greg Pak doing well in World War Hulk is show how powerful the Hulk is, by a point of he cause a lot of damage, but nobody get serious hurt. A Hulk guided by vengeance, he know if he uses much more of he got, people get killed (included all). The Worldbreaker persona born by a part of this Green Scar's persona, than is so much anger on Planet Hulk when the true us coming he cannot hold himself. Even of so much anger, he can hold enought to sacrifice for humanity. But this Immortal Hulk is so different, he is not only powerful, but he is smart enough to disgrace Banner's life.