The magical Star Rod.

The Star Rod is a magical item with the power to grant the wishes of the people of the Mushroom Kingdom. It is in the possession of the Seven Star Spirits, who use it to grant the wishes. It is first seen in Paper Mario. Bowser steals it and imprisons the Star Spirits. Not long after, he uses it to defeat Mario and lift his castle into the sky with Peach's castle on top. Mario goes on the adventure of Paper Mario to stop Bowser and take back the Star Rod. The Star Rod that is featured in the Super Smash Brothers series is not this Star Rod, but from another Nintendo franchise, which is Kirby.