Secret Altar
Area Area Four
Portrait Ghosts King Boo
Floor basement

The Secret Altar (Japanese: 秘密の祭壇 Secret Altar) is the final room in Luigi's Mansion. It can be found by Luigi in the fouth area, and is where the game's final boss, King Boo, waits.


Luigi's Key retrieved in The Artist's Studio allowed him to gain entry past the forcefield guarding the Secret Altar. Stepping inside the shiny, golden room, Luigi found King Boo, staring forlornly at a painting of Mario. This was no mere painting, however, as the red-clad plumber himself was trapped inside. As Luigi approached, King Boo launched into a long speech about the two brothers. How Mario caused him so much trouble in the past, and how Luigi vacuumed up all his friends and minions into his vacuum. King Boo tells Luigi that he is not afraid of the ghost hunter, only the Poltergust 3000 he carries on his back. His final threat is for Luigi to join his brother inside the painting. King Boo transforms Mario's painting into a painting of Bowser, which he flies into. The Bowser painting inhales Luigi and the green-garbed ghostbuster finds himself on the roof of the Mansion, staring down King Boo inside the reanimated body of Bowser. King Boo attacked Luigi with many attacks.

King Boo's Attacks

  • First, King Boo could blow fire at Luigi, setting the ground on fire (and thus, untouchable) for a short time.
  • King Boo could also suck Luigi into his giant jaw, chewing him up and spitting him out. The Boo leader would also compound the damage by following it up with his fire attack.
  • If Luigi got too far away from King Boo, he would leap into the air, and crash back down, trying to flatten the poor plumber.
  • If Luigi manages to get behind King Boo, the ghost would swing Bowser's tail, trying to sweep him away.
  • King Boo would also roll bombs like bowling balls down the roof toward Luigi, which could either hurt the plumber should he run into them, or explode, setting him on fire.
  • When Luigi has King Boo exposed, Bowser's head would follow, blowing chunks of ice at Luigi. This attack could hurt Luigi the most.

Luigi noticed a fatal flaw in King Boo's attack pattern: his bombs. Attaching one of these giant explosives to the Poltergust 3000's nozzle, Luigi aimed and fired at Bowser's head. This blew the head clean off and forced King Boo out into the open. Luigi could begin whittling away at his monstrous 500 HP, while avoiding the Bowser head's ice attacks. King Boo would eventually break free and retreat back into the safety of Bowser's body, and the head would reattach itself. The process then repeated.

When Luigi drained King Boo's health to less than 200, the ghost started putting his head on backwards. This caused him to go on a small rampage, destroying anything in his path. Eventually, he would turn the head right-side up, and the battle would continue normally.

After a few rounds, Luigi completely depleted King Boo of energy and the leader of the Boos was sucked into Luigi's trusty vacuum cleaner. His crown (a red jewel worth the same as a single coin) became Luigi's, and the Bowser body fell in two pieces, unable to move without King Boo's guidance. Luigi was warped back to the Secret Altar, where he finally recovered Mario's painting to return his brother to his former self.

The Secret Altar contains three chandeliers, one of which holds a Blue Jewel. On the west wall is a stone lion's head on the other side of which is the Bottom of the Well. On the east wall is a mirror flanked by two torches burning with incense. If Luigi vacuums the incense, one torch will give him money, and one torch will give him some gold. Two similar torches are found at the rear of the room on either side of Mario's painting.


  • It is possible to get 1'100'000 gold in the Secret Altar. 600'000 from the two torches to the right of the room, which have 1 gold bar, 20 bills and 20 coins, and 500'000 from the chandelier closest to the entrance, which has 1 sapphire.
  • In between the two torches to the right, there is a mirror, that when scanned will have slightly messed up visuals and audio, but will still teleport you back to the foyer.
  • This room is rarely seen with the lights off