World 4-Castle (New Super Mario Bros. 2)
Mario begins under a Spiked Ball enclosed in Snake Blocks. Two ? Blocks can then be found, one of them containing a Super Leaf or a Super Mushroom. Snake Blocks can then be found pushing Spiked Balls around the floor. A multi-coin Brick Block can then be found very near to a Fire Bar. This is followed by an area with Snake Blocks on the ceiling controlling the fall of Spiked Balls, where a Dry Bones can be found. A Roulette Block follows, along with more Fire Bars. A P Switch can be found below the first Star Coin, causing Blue Coins to appear. An area with more Snake Blocks on the ground, a single Dry Bones, a Fire Bar and several Spiked Balls can be found. This is followed by the Checkpoint Flag, where another Super Leaf can be found in a ? Block. Another area where Snake Blocks push the Spiked Balls on the ground can be found. More Snake Blocks can be found with a Dry Bones, where Spiked Balls occasionally drop down from the ceiling. This is followed by a Fire Bar and a red pipe below another ? Block with a Super Leaf. After that comes a fork in the path separated by Snake Blocks. The upper path has a single Giant Spiked Ball moving quickly while the bottom has two slow-moving Giant Spiked Balls. Both paths leads to the boss door.
The boss that Mario has to defeat here is Morton Koopa Jr., taking place in a room with slanted platforms. His attacks are making Spiked Balls roll down towards Mario and also shaking the ground to stun Mario. Mario needs to stomp on him three times. He performs his shell attack each time while spinning down the path the Spiked Balls would originally leave the room, then he returns with a large Warp Pipe on the ceiling. Defeating him takes Mario to World 5.