What opens the door

Exploration Stage: Traveling Circus
From: Mr. Black
Description: The door with all the parts installed looks somewhat mysterious, doesn't it? I wonder what kind of "tricks" we will see when we open this door? According to the note we found, we need the crystal key. Diggs gave us a fake one, but we won't be easily fooled. Let's find the real key.
Completed: What an unusual key. If I had left it to my men alone without your help, I would not have found it at all. It looks like the handle head of a walking stick, but the attachment is too small for that. Maybe it came from a magic wand. See, it fits perfectly! Okay, let's turn this thing on its head...