Wario Land 3: Part 43: Cave of Flames (Gray Chest)

After obtaining the third Green Music Box, a hole opens on the volcano's south side, leading into a fiery level. To reach the Gray Key, break through a path of Fire Blocks with Hot Wario, then use a portal to traverse to the opposite side, ignoring enemies thrown at it. Create an opening, then roll through the slope to reach the Gray Key and bring it to the Gray Chest. The Gray Chest treasure is a Scepter, which purifies the murky black water found in The Big Bridge, The Frigid Sea, and Sea Turtle Rocks, revealing hidden doorways.