Rooftop (Luigi's Mansion 3)

The Rooftop is the highest point of The Last Resort in Luigi's Mansion 3. The final battle against King Boo takes place here. The Virtual Boo has no map for the Rooftop or the stairway leading up to it; it simply displays Luigi's location as "???". This area is only referred to by name on the file selection screen.

Luigi (and a recently freed Mario) access the Rooftop through the secret door in the back of the Master Suite, climbing up the inside and exterior of the hotel to reach the very top, where Princess Peach's portrait has been set up. At Mario's urging, Luigi frees the Princess with his Dark-Light Device; their reunion is suddenly interrupted by King Boo appearing behind them. Surprised that Luigi has made it this far and deriding his minions (chiefly Hellen Gravely) as useless, King Boo attempts to trap everyone, including Professor E. Gadd and three Toads in a single portrait; he successfully captures everyone except Luigi, who was saved by Polterpup. Enraged by Luigi's apparent defiance (actually mortal terror), King Boo decides to destroy his nemesis personally, beginning the final battle.

Battle
King Boo begins by summoning barrages of lightning bolts onto the Rooftop; Luigi must avoid this by going to a part that does not shine purple light. The ghostly villain can also slam his tongue into the roof; Luigi must sidestep the slams before using a Burst to dodge the follow-up swinging attack. King Boo can also shoot burning spheres from the gem on his crown; once again, Luigi must keep himself out of their path to avoid damage. King Boo then throws out a spiked ball that cracks open to reveal some bombs; Luigi must avoid the one that immediately detonates while picking up one of the remaining bombs and launching it into King Boo's open mouth. The resulting explosion knocks King Boo onto the Rooftop in a stunned state, allowing Luigi and Gooigi to grab his tongue with their Poltergusts and slam him into the roof three times.

After recovering from the beating, King Boo resumes his assault by summoning a clone of himself - it can be distinguished from the real deal by its darker eyes and fewer teeth. Aside from more intense versions of his previous attacks, King Boo and his clone can use a spinning tongue attack that strafes the Rooftop; Luigi needs to find an arch in the tongues and go under it to avoid damage. The ghosts can also perform a series of body slams on the roof, with the real King Boo generating a shock wave around himself with every impact; Luigi must watch the shadows to avoid being squashed, using his Burst to dodge the shock waves. When the Boos start throwing spiked balls, one contains bombs and the other has random objects; Luigi must launch a bomb back into the real King Boo before teaming up with Gooigi for another slam attack.

Angrier than ever after two rounds of slamming, King Boo drastically enlarges the portrait containing Luigi's friends and family, threatening to trap the entire hotel and everyone in it (including himself) to finally seal his nemesis away. Luigi now has four minutes to finish King Boo before the portrait comes down on the Rooftop, a task made more difficult by King Boo's most vicious assault yet. Summoning two fake versions of himself, King Boo uses deadlier versions of all his previous attacks, as well as a new move where he and his clones toss six spiked balls into the air in order to rain dozens of bombs over the Rooftop. After weathering King Boo's attacks, Luigi must once again launch a bomb into the real villain's mouth; a final round of slams from him and Gooigi proves enough to finally defeat King Boo. After being sucked into the Poltergust G-00 and releasing the gem on his crown, the super-sized portrait returns to normal size and the entire hotel collapses, sending Luigi and Gooigi tumbling from the Rooftop; fortunately, Polterpup is able to catch the former before he falls to his doom.