Defeat the giant spear man (Invade Wario Castle)
From the Super Mario Wiki
The stage is composed of various similar looking rooms, each with one entrance on the left side, two exits on the right side and one or two enemies in the middle of the room. The type of enemy differs from room to room so the player can view them as landmarks. The corridors lead to six different dead-ends, from which one houses the said giant spear man.
Hidden Treasure: Egg
The hidden treasure of this level, the Egg, is located behind one of the many doors in this level. In order to reach it the player should head left from the start, pass the rats, move through the left door, pass the Punch, move through the left door, pass the Grunt and move through the right door.
The treasure found in this stage is a reference to a Yoshi Egg.
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