When attempting to make it to the top of Overlook Mountain to unravel the Mushroom Kingdom in Paper Mario: The Origami King, you will find your path blocked by several metal thwomps. You have to get past them, and you need to use the star at the top of the tree to do so.
The only way to get past the thwomps is to use the star. To activate it, run up the slope to the top thwomp and approach him. Several thwomps will come down from the sky, forcing you back down the slop to the bottom and prevent you from continuing forward. When the final thwomp lands on the ground, a star appears at the top of a tree to your left. All you have to do is hit it with your hammer to knock it down.
The star will bounce around the area when it lands. All you have to do is approach the star and have Mario touch it. When he does, he will become his signature rainbow color, rapidly switching between various colors from all over the rainbow, signifying his invincibility. You can now approach the thwomps and hit them with your hammer to send them flying. When you make it to the final thwomp, you can now continue forward, and you don’t have to worry about them blocking your path again.