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.

After rescuing Mario, Luigi accesses the Rooftop through the secret door in the back of the Main Observation Room, 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 the three Toads in a single portrait. He successfully captures everyone except Luigi, who was saved by Polterpup. Angered that he did not capture Luigi, King Boo attacks him personally, commencing the final battle.

Battle
King Boo begins by summoning barrages of lightning bolts onto the Rooftop; Luigi must avoid this by going to a spot that does not shine purple light. This phase is similar to the mission "A Nightmare to Remember" from Luigi's Mansion: Dark Moon. His other attacks include slamming his tongue into the roof, which Luigi must dodge by sidestepping the slams before using a Burst to dodge the follow-up swinging attack, and shooting burning spheres from the gem on his crown; once again, Luigi must keep himself out of their path to avoid damage. Luigi can technically Burst the spheres out of the way, although this must be carefully coordinated, or he will take damage. King Boo has different reactions depending on whether or not Luigi gets hit by the former's attacks: he laughs if Luigi gets hit, and snarls in anger if he does not. When King Boo throws a spiked ball, it 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. However, if the player takes too long to get set up to slam him, King Boo will eventually recover before violently pulling his tongue back in (causing Luigi and Gooigi to fall on the ground if they were grabbing his tongue), laughing at them, then restarting the cycle all over again.

After the first round, King Boo summons a clone of himself - it can be distinguished from the real King Boo by its darker eyes and fewer teeth (only the molars are present). 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.

After two rounds of slamming, King Boo drastically enlarges the portrait containing Luigi's friends and family, attempting to trap the entire hotel in it. Luigi now has four minutes to defeat King Boo. Summoning two fake versions of himself, King Boo uses stronger 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 dodging King Boo and his clones' attacks, Luigi must once again launch a bomb into the real one's mouth; a final round of slams from him and Gooigi takes him down. After being sucked into the Poltergust G-00 and releasing the gem on his crown, the large portrait returns to normal size and the entire hotel collapses, due to structural stress from the battle, sending Luigi and Gooigi tumbling from the Rooftop; Polterpup catches Luigi before he hits the ground.