Vexing Doors

Vexing Doors is an e-Reader level for Super Mario Advance 4: Super Mario Bros. 3. This card was released in Series 2 in Japan. Its official difficulty rating is ★★★★☆. The level contains five Advance Coins. It was initially released only in Japan, but became available internationally when the game was released on the Wii U Virtual Console in 2016. The key art featured Lemmy Koopa.

Layout
The level takes place in a Ghost House. The first room is haunted by a Boo and a Big Boo. There are three doors:
 * The first door seen takes Mario to a room with spikes floor. He must ride a Snake Block to reach an Advance Coin and back.
 * The third one leads to a small room with a Boo and a ? Block.
 * The second one takes Mario to more doors.

Entering the second door, Mario finds himself in a room with another Advance Coin and three doors, but only one of them is visible without pressing a P Switch.
 * The one in the far left leads to a room with two doors. Both take Mario to the same room (filled with invisible ? Blocks) but the upper one allows Mario to get an Advance Coin.
 * The second invisible door and the visible one basically take the player to the same room, but the P Switch door takes them to an Advance Coin room first.

The next room has more doors:
 * Entering the one in the left corner, Mario reaches a room before the Big Boo battle, with three doors that take Mario back to the second room. The last one leads to the battle.
 * The one over Coins can be accessed by pressing a P Switch (only accessible by entering the Advance Coin door in the second room). Mario can collect the last Advance Coin and a Control Coin here.

The battle with the Big Boo is similar to the previous one: Mario must toss three Ice Blocks at him, while avoiding two regular Boos. One of regular boos is faster than usual.