Uh-oh! It looks like someone pulled a vanishing act on the textbox that's supposed to say:
"Throne Room of Fire,
Press X to Enter."
"Team Up!"
Both the textbox, and it's Team Up! button are missing, on both the northern entrance and the southern entrance to the dungeon. I ended up having to brute force my way through the dungeon solo ( not the easiest thing to do on an Ice Wizard ) because I had nobody else online to help me!
