Treacherous Halls

Treacherous Halls is a promotional e-Reader level for Super Mario Advance 4: Super Mario Bros. 3. Its official difficulty rating is ★★★★★, making it one of the more difficult e-Reader levels. Much of the level consists of stomping enemies over spikes to cross them. Many Piranha Plants also appear, as well as two Flurries, one of which has to be ridden to collect an Advance Coin and also a 1-Up Mushroom. Boom Boom is fought at the end of the level. It was initially released only in Japan, but eventually became available internationally when the game was brought to the Wii U Virtual Console in 2016. The key art for the card featured Boom Boom.

Enemies

 * Grand Goombas
 * Big Koopa Troopa
 * Colossal Koopa Paratroopa
 * Goombas
 * Koopa Troopas
 * Buzzy Beetles
 * Red Paragoombas
 * Piranha Plants
 * Venus Fire Traps
 * Flurries
 * Dry Bones
 * Koopa Paratroopas
 * Spiny
 * Boom Boom

New level elements

 * Flurry