Things You'll Need
Instructions
Enter the room with the Crystal Switch in it. Hit the Crystal Switch and stand on the block that is lowered in the middle of the room (you can hit the Crystal Switch with any of your attack weapons).
Hit the Crystal Switch a second time to lower the other blocks.
Open the chest in the room to get a small key. Then stand on one of the blocks and hit the Crystal Switch to make the blocks rise.
Walk east until you find another Crystal Switch. Ignore this Crystal Switch and head south. The room you enter to the south is the room with the Nightmare Key.