The bros find themselves on Mount Brrr. There are patches of ice the bros will spin across. There are Buzzy Beetles here. You can't hurt them when they're in their shell. Climb up the stairs to find a gap in the rocks. Send in Paper Mario for some items. Try to go east and the bros will hear something loud. Go east. When you try to cross a patch of dirt, the ground rumbles again. Starlow thinks it's coming from above.
On the summit, Big Bob-omb, along with Morton Koopa Jr., Iggy Koopa and Lemmy Koopa, tells minions to fire something. It's a cannon launching cardboard platforms. Another cannon launches paper minions. Some of the cardboard nearly lands on the bros. Unfortunately, the way ahead is now blocked. Paper Mario is inspired by some nearby cardboard. Press (A), (B), then (Y) to use the Trio Drill. Use it to tunnel underground. You can also tunnel under spots marked with "X" to get items like beans without having to pop up each time. Hold (Y) to do a Drill Dash. Use it on the rock under a cardboard platform to destroy it. Starlow notices the question mark on the platform the bros just Drill Dashed under. Trio Drill into it from above to get Heart Boots. Use the Trio Hammer so you can go east into a cave.
Inside the cave are more Buzzy Beetles. There are dirt walls in the cave, so use Drill Dash to climb them. Drill Dash repeatedly into cracked rocks to destroy them. Beware of the saws on the walls. Drill Dash to exit the walls. Higher up is a puzzle. There are spikes in the gaps between the walls to avoid. Move them around by Drill Dashing into the pink ! Block on the wall. There's a crack in the wall near it. Destroy it and move the pink ! Block to the lower position to move forward. There's another crack in the wall on the left side. Cross over to that side and go west.
The bros find themselves outside again. Someone says "Whoooooa." It's Bowser Jr., and he's higher up on the mountain. Paper Bowser Jr. is playing with the papercraft. Bowser Jr. leaves to play with it. Toadette appears, saying she knew there was a new one already. She says they need a new papercraft as well. She's got plenty of ideas, but not as many Paper Toads. She also needs a safe place to work. That cave to the east probably won't work. Luigi says there's no such thing as a safe place in this terrifying world. Toadette says she's heard of a Toad Village to the west, but it's much farther away than the bros anticipated. The path is also a puzzle. Once it is solved (and it can be solved), the bros will have a clear path to the village. Hop in the nearby pipe and hit the ! Block so you can return easily.
Drill up the wall and start breaking through the cracks. Toadette calls to them when they approach a puzzle, saying the bros are about halfway to the summit. Fiddle around with the puzzle contraptions to find a path to the village. The sign says to push the blue crescent and pink target stones into the corresponding slots. The stones can only move on the tracks. The blue crescent is close by. Drill Dash to move it up, left, up, left, down, right, then up. This makes corresponding platforms appear out of the mountain. Drop down to Toadette's level and go west. You'll find Bullies and Paper Sombrero Guys here. To reach the top of the middle area, go to the left and climb using the orange springs. Trio Grab to the other side. Go back east.
Hit the ! Block to make the rocks between the puzzles disappear, then go up to the puzzle. Move the pink target stone up, right, down, right, down, left, up, and left. This makes the corresponding platforms appear from the mountain. Go back east into the cave for a puzzle involving dodging saws in the walls. You'll find beans in the walls and get a Paper Speed Bracelet if you clear it. Back outside, take the dirt path as high as you can go to cross to the Toad. Go west into the Toad Village. A Toad welcomes them to the village. Starlow says they need a way to climb the mountain and deal with Bowser Jr., so they'll need to save more Paper Toads.