Dark Moon - S4.E25

Dan and the others have arrived safely on Earth to find a mysterious dark moon in the sky and all the people missing, having been imprisoned in the dark reverse dimension of Earth. Mag Mel sends Mechtogan Titans of five different attributes to destroy the Earth's core and in the process, destroy Earth with the resulting explosion destroying New Vestroia, Vestal, Neathia and Gundalia in the process. Everyone splits up in order to take out the Titans when all of a sudden Spectra and Gus show appear to help, Spectra having somehow been able to escape Bakugan Interspace at the last minute. Despite defeating the Titans, another wave is suddenly dispatched by Mag Mel and Dan is agonized to see all of his friends taken down so easily. With help from Marucho and Tristar about the Gate and Key, Dan and Drago break free and lure Mag Mel and Razenoid to the dark dimension where they're final showdown will begin.