The bros have saved all of the Paper Toads, so it's time to head to Mount Brrr via Gloomy Woods. Head towards the entrance of Gloomy Woods. The way north is blocked off, but a Toad mentions the nearby spring platform. Trio Glide onto the nearby platform, then to the tall platform to reveal that it is a spring. It launches the bros into the clouds. There are many coins and enemies here. Go east to find more. Drop through a hole to land on the ground. The one to the southwest will drop you on the cardboard platform forming a bridge to Gloomy Woods in northwest Sunbeam Plains.
Starlow notes that Gloomy Woods seems gloomier than before and thinks something is going to pounce on them. The woods certainly are darker here. Some Swoops fly by, startling everyone. They have to keep going. Starlow hopes Luigi can keep it together. Due east is the Toad Village, but you can't reach it from here due to the bridge. Walk to the west and send Paper Mario up the spider web. Hit the ! Block to make the roots ahead disappear.
Walk to the north and you'll find a tree with cracks in it that look like a mouth. Approach it and eyes light up. Swoops appear from the tree, reveal it's really King Boo and some Boos. They make roots appear, trapping in the bros. Luigi tries to escape that way, but fails, and notices the Marios are gone. He breaks down. Starlow says "Ow" and Luigi gets up. He's on his own. Walk to the east and Starlow says to get her out of the glowing plant. Starlow escapes, upset she got grass clippings in her mouth. Starlow makes the situation worse by making it very clear that Luigi's on his own. She realizes she needs to work on her pep talks. She tries encouraging him, saying he's tall, got a great mustache, and had a whole year named after him. It's basically Luigi RPG now. The pep talk works until some Swoops fly by.
Walk to the north. Luigi's rather slow on his own. Go west. Some Boos laugh and fire blocks the path behind you. A gate to the north opens and you have 1 minute, 30 seconds to cross through it. You can't take a path with Boos on it, so hop over the purple fire. You'll come to a fence and the Boos will laugh again. Take the path where the glowing plants don't flicker. There's another gate ahead. Leaves will start falling. Cross on the side where the leaves fall straight down. Cross through the gate to stop the timer. Go north. It's another challenge to cross the gate, this time within 2 minutes. Hop over the moving purple flames. When you step on the wooden platforms, you'll hit boost pads. There are some wide stairs ahead. Step on the stairs that don't have Boos on them. Near the gate, shadows appear. Step in the middle of the circle without touching the shadows and step out on near the gate. Go through the gate.
Luigi sees someone who looks like Mario from behind. He tries talking to it, but it's really a Boo. There are more Mario illusions here. Walk up the cardboard platform to the left to find a green block. Hit it to make a platform appear. Walk farther to the left and you'll find many Mario illusions staring at something. It's the real Mario, dangling from a tree. Jump and Mario wakes up and lands on Luigi. Starlow's happy to see Mario, since it was touch and go with Luigi. Now they need to find Paper Mario. Have Mario hit the red block to make two more platforms appear. Use them to cross to the right side of the clearing. On the other side, Luigi spies Paper Mario, or someone like him. Go south.
Loop around the water and go north. Use the Heal Block and save your game. Paper Mario's no longer in the area. One of the trees will move. Check it out. Paper Mario will appear. The bros think they've reunited with Paper Mario, but it's really King Boo. He'll breathe fire to start. Some of it will fly over the bro's head. He will then inhale the fire, so jump to dodge it. His crown is pointy, so don't use jump attacks. He'll split into 5 copies and approach the bros, then disappear. Time your counter with the hammer. He'll summon a Paper Boo to bring in Paper Mario. He says not to attack him or his minion if they like Paper Mario. All you can really do is damage King Boo with counter attacks. Use your turn to heal or use the hammer on the Paper Boo. After a while, King Boo will get angry. He'll breathe more fire and split into more copies. This fight is going to take a while. When King Boo is defeated, the Paper Boo will toss Paper Mario back to the bros. Starlow wants to get out of Gloomy Woods and meet up with Flutter to get a ride to Mount Brrr.