Instructions
Enter Bowser's Castle and avoid the lava traps, falling platforms and undead Dry Bones enemies. Go into the menacing Bowser Door after the checkpoint.
Continue until you encounter a long hallway. Bowser will launch huge fireballs toward you in this hall, so duck into one of the indentations in the floor when a fireball is close.
Confront Bowser at the end of the hall. You can defeat Bowser by either hitting him with enough fireballs if you have the Fire Flower power-up or by hitting the switch on the far-right side of the room. When Bowser jumps in the air to slam the ground, run under him and jump on the switch to drop Bowser into the lava pool below.
Run from Bowser when Kamek uses his magic to grow him to a gigantic size. Bowser will pursue Mario through a series of platforms, so time your jumps carefully. Position yourself between Bowser and the brick walls in your path. Jump at the last second to allow the fireball to destroy the wall section.
Stomp on the switch at the end of the corridor Bowser chases you through to finish off Bowser and save Princess Peach.