Rules: Galactus has no Herald for support. Morals on means that Majestros and Sentry cannot destroy Galactus, but must find a way to redirect Big G's hunger. Majestros and Sentry can use any ability within their repertoires; Majestros can also use the Creation Blades, but Sentry cannot go Void.
Instead of fighting Galactus they simply work together to create a renewable perpetual energy source that will feed Galatus for the next thousand years and leaves plans behind to create the device again every thousand years, thus allowing Galatus to wonder the galaxy for the next thousand years never having to feed on another planet... Thus he is defeated and Earth is saved.