The middle of this floor is part of the treasure path, but the four rooms in the area contain nothing but monsters. The outer area is the main path. Follow the outer wall in either direction until you come to stairs in the northeast corner. The nearby chest contains a Wind Flute, but is guarded by a powerful Green Dragon. This Dragon is similar to others you've fought, but vulnerable to Lightning. Its defense is quite high, and is best pierced with Berserk or a Blood Sword. The stairs lead to the Emperor's room.