This level will introduce Boos to the game, which anyone familiar to the Mario series will know, as long as you face them, they won’t come after you. Turn your backs to the Boos and they will chase after your character. At the start of the level, head right and hit the top ?-Block to find a power-up (this level prioritizes Fire Flowers). Ignore the stairs going down and continue up the stairs next to it. When you reach the Boo painting, if you have the Cat Suit, climb the wall to find a clock on an invisible cloud platform. Leap down and jump into the painting to reach a room full of Peepas.
The bonus room here will rotate, with the Peepas moving in a set way. Wait on the bottom until the room rotates around, while dodging the enemies, then quickly grab Green Star #1 on the left side. Upon leaving, jump on the sofa you see and sit still, as it will rise into the air, allowing you to grab the Stamp. Proceed through the door at the end of the hallway. There are a bunch of bookcases in this area, but also a bunch of Boos. In this library, you’ll need to stand on top of the bookcases on the left side to make them move, which will eventually reveal Green Star #2.
Ignore the ?-Blocks and head right to the Checkpoint Flag, checking the top ?-Block here for another power-up. Continue heading right to find a Big Boo, then check the mirror to notice there’s a 1-Up Mushroom at the screen side – you can reach it by walking onto the cloudy platforms. Go up the steps and ignore the green pipe, as it is fake. At the split, go left if you want to grab a clock and a Super Mushroom from an invisible ?-Block, but otherwise go right. You can make a leap out to the cloudy platforms past the door for some coins, but it’s not worth the time. Through the door, you’ll end up outside where the entire section is filled with Peepas and fake items. Just rush past everything to the next door to return inside.
Grab the clock to the left for a bonus 100 seconds, then dash all the way right to the sofa. Ride it to the second level and use the pipe to spawn Green Star #3; the pipe is fake, but it will make the Green Star appear once it’s gone. Jump down and enter the door to reach the final area, where you just want to hold right and jump over the Peepas while avoiding the Big Boos. The first Goal Pole here will be fake, so keep moving to the right until you find the second, and real, one.