Point 4 is all about timing. You need to wait for steel blocks that are low enough to jump over or walk on. When a shorter block shows up, leap over it and Dash to get past the drop point before another block can crush you. If a large block comes down before you make it past, just run back to the ledge and wait again.
Boss Battle
Wendy O. Koopa doesn’t have to transform the battle area into any death trap-type chamber. Instead, she relies heavily on the deadly rings she shoots from her wand. Rather than blast you with balls of magic, Wendy creates deadly rings that bounce around the chamber.
These make it more difficult to dodge her attacks. As long as you stay ahead of her and anticipate the rings’ bounces, you can easily leap over her and land on her noggin. As usual, dodge Wendy’s shell attack, hit her head three times, and force her to retreat to the castle.