World 18-8 is the eighth and last level of World 18 of Super Mario Challenge from Super Mario Maker for Nintendo 3DS. It is also the last level that can be played in the Super Mario Challenge mode, as World 19 is played in the Coursebot. This is also the only Castle level which looks like the Castle at the end of the 10 Mario Challenges and the 100 Mario Callenges.
The level begins with an empty room with three Warp Pipes and a Koopa Troopa trapped in the wall, which indicates that the player needs a Koopa Troopa to get through. The first Warp Pipe takes the player to a room with Munchers and a Bob-omb. Unless the player has a Koopa Troopa or a POW Block, nothing can be done here. The third Warp Pipe takes the player to a room where they can get the Koopa Troopa. Another notable thing in this room is a Bill Blaster that shoots Buzzy Shells. Nothing can be done with this unless the player has a Trampoline. The second Warp Pipe takes the player to a room with three Trampolines (two of which can only be used to help bounce out of the room) and unlimited POW Blocks from another Pipe. The player must use either a Trampoline or a POW Block (both not carried) to escape the room. Using the POW Block in the first Warp Pipe allows the player to get a Key. The Koopa Troopa is the only way to get a Super Mushroom, as it walks onto a Note Block, releasing a Lava Bubble. The Lava Bubble then hits a Bob-omb, causing it to explode. This Mushroom can (but not necessary) allow access to the second Warp Pipe without going back to the Koopa Troopa, however, it must be used to get a Buzzy Shell on Mario. As for the Trampoline, it allows a Buzzy Shell to activate a Vine in a ? Block. With the Key, the player can enter the Key Door at the top of the vine. After going through the Key Door, the player gets a Checkpoint Flag, although it is possible to skip it and keep going.
The player is blocked from moving right by Spinies and a Bill Blaster, which gives out Super Mushrooms. If the player enters the nearby Warp Pipe, the player enters a room with Burners. The player must pass the Burners while they are not active and reach the Fire Flower. The player can either go back the way they came or Wall Jump on the nearby walls and Ground Pound six Brick Blocks. The player can use the Fire Flowers to shoot the Spinies. After this, there are two more Warp Pipes. The player can only take the bottom one, as the top one can only be reached with a Propeller Mushroom. In the bottom Warp Pipe, the player has to shoot a Mega Bob-omb on the top level to release unlimited Mega Bob-ombs. The player must shoot a Mega Bob-omb onto a conveyor belt, which takes out two Buzzy Beetles on a Muncher. This lowers the red Bill Blaster, which shoots a winged Lava Bubble, which then flies to a Mega Bob-omb and causes it to explode. The player can now have access to the top Warp Pipe with the Propeller Mushroom. The player needs to use the Propeller Mushroom to get past the Grinders and One-Way Walls with help of Bumpers and Propeller Mushrooms from the Warp Pipe the player came in, and then reach the Warp Door. This takes the player to a room where they can get a second Checkpoint Flag and a Super Mushroom from a ? Block. If the player still has a Buzzy Shell from the beginning, they can get a Key.
Taking the Warp Pipe leads the player to a fight with a big Bowser Jr. in a Koopa Clown Car. After being defeated, the player gets a Key, and is able to use the Koopa Clown Car to get some coins. After unlocking the Key Door, the player goes to an empty room, where they can get a Super Mushroom or a Fire Flower from a ? Block, depending on their current form. If the player has a second key, they can get three 1-Up Mushrooms. The player has to take the Warp Pipe to where they can fight a Giant Bowser in a Fire Koopa Clown Car and a Magikoopa in another. A Spike Trap is found in the middle. In order to get to the Axe, the player must use the Fire Koopa Clown Car to break Hard Blocks.