Some of the fences in this level move along tracks. When you hit one of these fences (press the Dash button while latched on to the fence), it moves to the other side of the track. Use this behavior to reach new areas and avoid the obstacles in your path.
The first Star Coin is located in a hidden area. Find the Invisible Blocks at Point 2, then use them to reach the red pipe on the ledge to the right.
Enter the pipe to find the Star Coin floating in the center of a small room.
The second Star Coin is floating at Point 3. Move over the Star Coin and wait for the small fence to emerge from the lava. When it does, drop down to collect the Star Coin and grab hold of the fence. Jump to safety before the fence drops back into the lava.
When you reach Point 4, hit the fence to move it toward the Red Ring at the top of the screen. After you pass through the Red Ring, hit the fence to move it toward each of the red coins.
The last Star Coin is at Point 5, floating just above the lava. As you approach it, make sure the fence you’re riding is positioned above the track. Grab the Star Coin as the fence sinks into the lava, then jump to the smaller fence above you.
The final chamber has five chains hanging from the ceiling. Each chain is located directly over a pipe. When the battle starts, Ludwig von Koopa jumps to one of the five chains. When he does, enter the pipe directly under him to be launched up, knocking him to the floor. Run over and stomp his head while he recovers. When Ludwig tucks into his shell, avoid him until he leaps to another chain. Repeat the process to stomp him a second time.
After you stomp Ludwig two times, he uses a chain to swing back and forth across the room. Move to a pipe near one of the walls and dodge Ludwig’s fireballs. When Ludwig swings to the opposite side of the room, enter the pipe. This causes you to hit Ludwig as he passes above you. Stomp him one last time to complete the encounter and unlock World Six.