Go straight to the left in the maze. Open the treasure chest in the last room to get the compass. When you get the compass, go back to room 2. Don't go down the underground stairs for the time being. Come back later.

Defeat the monster in Room 2 and you will get a stone beak.

When you come to room 12, which is full of crystals, cut off the crystals and magic items, and then push the two boxes inside to form a square, in which a key will be dropped.

Come to the room on the left of No.7, where there is a little skull boss. Break it first, then bomb it, three times.