Boiling Blue Bully Belt
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Boiling Blue Bully Belt, or World 
Castle-4, is the fourth course in the seventh world of Super Mario 3D World, World Castle. It becomes accessible by beating either Switchblack Ruins or Red-Hot Run, World Castle-2 and World Castle-3 respectively.
Layout
True to its name, this course is set on many stone structures above a blue lava lake. Naturally, Bullies serve as the main enemies. Throughout this level, purple blocks with arrows that can be used as platforms from time to time.
The first area in the level has the purple blocks rising and sinking back into the lava, but has very few Bullies. After the Checkpoint Flag, Mario must traverse a series of cylinder platforms and purple blocks that emerge from walls, while dodging spinning spiked rolls. At the end of this section, there is a Warp Pipe that takes the player to the final section, where there is a tilting platform with three Bullies on it. After they are defeated, a path appears leading to three more purple platforms and the Goal Pole following them.
Green Stars
- Green Star 1: Near the start of the level, there is a Green Ring that Mario can touch to make eight Green Coins appear floating above some purple arrow blocks. Collecting them all will reveal the first Green Star.
- Green Star 2: This Green Star is inside a Mystery Box just before the Checkpoint Flag area. There, the character must push a Bully into the lava to get it.
- Green Star 3: The final Green Star is next to the second-to-last cylinder during the second area, floating above a smaller one.
Stamp
- The level's stamp is found on a small circular platform before the Mystery Box.
