★World 4 (Puzzle & Dragons: Super Mario Bros. Edition)
From the Super Mario Wiki
Special World 4, known as ★World 4 in-game, is the fourth Special World in Puzzle & Dragons: Super Mario Bros. Edition, and is a more difficult version of World 4, with a purple tint in the background and the grass and water brighter in color. This world consists of twelve levels and a Toad House. Wendy O. Koopa is the boss of this Special World and is fought in her castle and airship. Clearing ★World 4- unlocks Red Winged Yoshi as a Helper; ★World 4- unlocks Wendy O. Koopa as an ally, and Cat Luigi as a Leader.
★World 4-Ghost House
Upon reaching the branching path in ★World 4-, the player may notice a Gold Block in the center, between the green Warp Pipe and the sign. By hitting the block, the player can access a secret area, which leads to the secret exit of this course. In order to use the block, however, the player needs to clear more Light Orbs than both Water Orbs and Wood Orbs. This course does not contain any Light Orbs, however, so the player must bring an ally that can create them. Upon defeating the boss at the end of the secret path, the player unlocks ★World 4-4.