This is the final stretch before Wario. This level is a vertical climb through the castle's interior, filled with spikes, moving platforms, and a relentless assault of enemies. You'll encounter more challenging versions of previous foes, such as larger Goombas and faster Koopa Troopas. There are also fire-breathing statues and crushing blocks. A Superball Flower or Bunny Carrot is almost essential for this section. Look for a hidden block containing a Starman near the end, which can help you rush through a particularly difficult segment. This level is a true test of your platforming skills and patience.
Preparation: Try to enter this level with a power-up, ideally Bunny Mario for its float. If you find a Starman, save it for a section where you're struggling or need to bypass many enemies.