Rhythm of War. He wants to start the book with another DBZ fight, fine. I know it's futile, it's too early in the book to beat the super strong enemy. Keep reading. An airship appears. Fine. He spends a while explaining exactly how it works (boring, removed me from the narrative) and it's just an absolutely terrible idea. The series was already on thin ice, but I hated this idea, it soured me on the book as a whole, and it was the final nail in the coffin for the series.