Without the Grand Star, the sun of Bowser's near-complete galaxy undergoes a supernova and becomes a super massive black hole.

Everything in the universe begins to fall in.

The Lumas from the Comet Observatory, including the Luma who had faithfully accompanied Mario through his journey, throw themselves into the black hole in order to neutralize it.

The Lumas attack the black hole's singularity, and it soon disintegrates in a massive explosion.