World Castle-Castle: Bowsers Lava Lake Keep

Clear the Boomerang Bros on the first two platforms, avoiding Lava Bubbles. Wallride the left wall and wall jump to reach Green Star #1 in the crack just above the lava.

Use a Kick Bomb from the cannon to destroy the grey bricks on the back wall, revealing a P-Switch. Wall jump into the alcove above the P-Switch to collect the Stamp. Climb the tall wall on the right using the Cat Suit to collect Green Star #2.

Hit the P-Switch to lower the bridge. Cross the bridge, avoiding the Fire Bro and Ka-thunk. Past the Kick Bomb cannons, you'll find the Checkpoint Flag.

In the next area, switch to the Boomerang Power-Up. Run across the bridge with Lava Bubbles and use the boomerang to grab Green Star #3 over the lava.

Cross another bridge and jump on the small metal plate to reveal a hidden block containing a Boomerang Flower.

Defeat the two Ka-thunks and two Hammer Bros. If you have the Boomerang Flower, wait for them to jump and hit them.

Enter the Warp Box to face Bowser. Avoid his lava pools and Kick Bombs, as well as environmental hazards like pitfalls, lava geysers, and spikes on narrow paths.

Kick Kick Bombs back at Bowser. If you fall, a Warp Box will take you to a grated floor with more frequent lava geysers and narrower paths.

Continue to land Kick Bombs on Bowser until he is defeated.

Take the Warp Box to the Goal Pole area to finish the level.