Bowser's Last Stand

Kakushi Koopa Jō ( かくしクッパじょう Hidden Bowser's Castle, unofficially known as The Gauntlet or Bowser's Castle Redux ) is an e-Reader level for Super Mario Advance 4: Super Mario Bros. 3. The level contains five Advance Coins. The level is often described as the hardest among entire e-Reader levels.

Level synopsis
This level takes place within a Bowser Impostor's castle. Its entrance room contains some Gray Bowser Statues and a short lava pool with two Lava Bubbles. A Hot Foot and a Door are found at the end of this room. The door takes Mario to a vertical area divided into three sections. Mario must choose one of them and drop its Donut Lift to enter the corresponding door.


 * Left door: a room guarded by Boomerang Bros., Hammer Bros., Fire Bros., and a Sledge Bro. The Hammer Bros. hide an Advance Coin.
 * Middle door: a corridor over lava filled with Lava Bubbles. An Advance Coin is found above a moving platform.
 * Right door: a lava pool with jumping Cheep Cheeps. There is an Advance Coin after the platform rails.

They all contain a Warp Pipe that takes Mario to a longer corridor, where Hot Foots, Bony Beetles and Dry Bones are found. Upward Donut Lifts appear here as well, and can be used to collect another Advance Coin.

The next area is constantly attacked by Magikoopas. An Advance Coin is stuck inside a Brick Block cage, which Magikoopa can destroy (Mario can get it using a boomerang too). After that, Mario faces fire-breathing Gray Bowser Statues and jumping Gold Bowser Statues on falling spike platforms. There is another Advance Coin before the door.

The next room features Bowser Impostor's incoming Fireballs. The upper route is made of falling platforms and has more Fireballs. However, Mario can get an Advance Coin inside the Bowser Impostor's room. The lower route is made of stationary blocks, has Lava Bubbles and a few fireballs, but the player can't have the special coin fighting with the Bowser Impostor via the lower door.