Ruby Star

The Ruby Star is the fourth of the Crystal Stars Mario collects in Paper Mario: The Thousand-Year Door. According to the legend of the Crystal Stars as told by Grifty, the Boo heroine placed the Ruby Star in the Creepy Steeple in an effort to keep it safe. Eventually, Doopliss finds the Ruby Star and starts residing in the Creepy Steeple, using the Ruby Star to amplify his power and turn the residents of Twilight Town into pigs. After Mario defeats Doopliss for the first time, he seemingly collects the Ruby Star, though Doopliss and Mario are soon revealed to have swapped places, with Doopliss having stolen Mario's identity and acting as him and fooling his teammates, while the real Mario is left to be nothing more but a shadow. Joining up with the Shadow Siren Vivian, Mario defeats Doopliss again and recovers the Ruby Star for real, as well as his identity, with his shocked teammates realizing they were tricked and knowing Vivian turned out to be one of the good guys, prompting the defeated Doopliss to run away, soon after joining Beldam and Marilyn in their villainous endeavors. After Doopliss's defeat, Mario learns the move Art Attack to use in battles.

During the final battle with the Shadow Queen, when the Crystal Stars spread out to the locations as to where they were found, the Star retreats to Twilight Town, where its residents root for Mario and his team before the final round against the evil queen begins.