Beware of the Bouldergeist

Use the Launch Star on the Toad Spaceship to reach the Mansion Grounds. Defeat or avoid Bats and Spranglers, then head towards the mansion.

Inside the mansion, you'll encounter Bomb Boos. Press Y to grab and spin them into objects to explode them. Use a Bomb Boo to destroy the statue in the fireplace to reveal a Launch Star.

In the next area, use the Jump Spring to enter Sling Pods. Use the Star Cursor (press A) to grab and pull Sling Pods, launching Mario. Use these to climb the wall and reach the first Launch Star.

On the subsequent planet, use Sling Pods to collect 5 Star Chips. A Pull Star will appear once all chips are collected. Use it to reach another Pull Star within a rotating comet, then use the Launch Star to proceed.

On the Bouncy Ball Planet, drop onto the Bouncy Ball core and grab the 1-up Mushroom. Wait for the exterior holey layer to align, then use the Ball to jump into the Launch Star. Watch out for Floating Mines.

In the final boss area, you can purchase an Extra Life Mushroom or a 1-up Mushroom from the Luma for 30 Star Bits.

The Bouldergeist will throw boulders, some of which turn into Bomb Boos. It will also cause stalagmites to grow. Grab Bomb Boos and spin them into the Bouldergeist to break its rocky exterior (3 hits).

In the second phase, the Bouldergeist creates giant rock arms. Avoid its punches and flattened attacks. Spin Bomb Boos into its body (not arms) three times to reveal its ghost form.

Throw a final Bomb Boo at the Bouldergeist's ghost form to defeat it and obtain the Power Star.