Grandmaster Galaxy is the final galaxy featured in World S of Super Mario Galaxy 2 and is the last galaxy that can be unlocked in the game. The galaxy is a series of obstacles courses that, as a whole, is much more difficult than any other galaxy before it. Successfully crossing the obstacle courses will award you with a Power Star. After fulfilling miscellaneous objectives inside and outside the galaxy, a daredevil comet will appear. You must then complete the entire galaxy again without getting hit once.
The Ultimate Test
This mission is split up between six areas, with nearly all of them ending with a launch star to the next area:
- The first area requires you to use Yoshi. The purpose is to have Yoshi grab and swing from the flower objects floating in midair. The obstacle course is littered with Paragoombas, Bullet Bills, and other hazards.
- The second area is made up of Flipswitch Panels that have to be turned yellow. As the Flipswitch Panels go, stepping on one changes the color from blue to yellow and stepping on it again changes it back, though having them all match can prove to be frustrating when considering how the panels are laid out. Lasers chase Mario as you complete this course.
- The third area gives you the cloud suit and has you traversing within the boundaries of electrical currents above and below you.
- The fourth area contains the platforms that flip when Mario does a spin jump. Vanishing surfaces, projectiles and more lasers help complicate the area.
- The fifth area is an electrified obstacle course that Mario must cross using pull stars. Paragoombas return to get in Mario's way.
- The sixth and final area is populated by Hammer Bros. and Boomerang Bros. A Comet Medal is found in this area, off to the right by a Hammer Bro. The power star will appear when you defeat the three Boomerang Bros. found in the furthest back part of the area.
Prankster Comet: The Perfect Run
This power star is literally the last star in the game. In order to access this mission, you will need to have collected every comet medal (including the one in this galaxy) and have also deposited 9999 Star Bits at the Toad bank on Starship Mario .
This mission is under the daredevil comet and to obtain the star Mario has to complete the six areas again without getting hit or hurt by anything. There are no checkpoints like there were in the previous mission. Also the paragoombas in the first area was swapped with tougher enemies, along with some additional obstacles thrown in for good measure, and the music originally used on the level is replaced by music from the original Super Mario Galaxy game. The latter part of this galaxy must be completed as Cloud Mario. Once Mario acquires the suit he won't be able to lose it since there are no other power-ups and getting hurt, which typically takes away a suit, will just send Mario back to the beginning of the mission.
Once you reach the final area and the Boomerang Bros. are defeated, a launch star will appear instead of a power star. The launch star shoots you onto a small piece of land reminiscent of the The Gate from the Comet Observatory. Rosalina and the last power star await Mario on this island. Rosalina shows her gratitude for getting all the stars; and when Mario returns to Starship Mario, Rosalina will appear on the starship as well.