Cosmic Power Star

The Cosmic Power Star (sometimes known as Saphire Star or Blue Power Star) is a type of Power Star that unlocks the ability to play as Cosmic Mario/Luigi. It makes it debut in Super Mario Galaxy 3 - Neverending Galaxies. However, this star is very difficult to obtain. First you need to complete Universe 1, all power stars and even the special ones. After that complete whatever galaxies that are in Universe 2, you will have to complete more galaxies if the game updates. After that, a special mission in Backyard Galaxy will appear, and a text will appear saying "BLUE POWER STAR HAS BEEN DETECTED!". This mission goes under Daredevil Comet conditions, has some tricky obstacles and has a time limit set for 3:50. After the long journey, Rosalina gives you the Cosmic Power Star. After you have collected it, a special cutscene will show up. It shows Cosmic Mario and Cosmic Luigi running across Starship Mario. Mario and Luigi try to catch them, but the Cosmic bros. escapes. Then, the cosmic comet crashes towards a new galaxy. You will realize you are playing as Cosmic Mario and Cosmic Luigi. If you complete the mission, you can explore special missions as Cosmic Mario/Luigi at any time.