In the final area, after defeating Hellen Gravely — Luigi rescues Mario from the painting. Mario leads Luigi to the rooftop of the hotel to save Princess Peach.
No real surprise… King Boo is the final boss in Luigi’s Mansion 3. Find out his tactics and how to defeat him in this Luigi’s Mansion 3 Final Boss Guide.
King Boo has a few different attacks, which get amplified for each of the three phases of this final fight.
In phase 1, it’s just King Boo himself. In phase 2, there are two King Boos, and of course the third and final phase has three King Boos.
King Boo Attacks
King Boo will do this lightning attack which is easy to avoid. Just be in the square that is not illuminated by purple. The tip is to return to the center after every strike.
This allows you to cover the distance to any square as quick as possible.
The vertical tongue attacks are followed by a final horizontal sweeping attack which Luigi needs to jump (Burst) over. For a single King Boo, you can consider staying in the far corners as the sweeping tongue can’t reach there. But jumping would probably be easier.
For multiple King Boos, it’s a bit harder. Their sweeping tongue attacks vary in height, so you’ll need to examine whether you need to Jump or simply run underneath.
The fireball attacks are also easy to avoid. You can use Poltergust to influence the fireballs path and blow them away. You can also use Burst to send any fireballs away.
I recommend staying at the bottom edge. Using Burst makes Luigi vulnerable during a brief recovery period. By staying near the edge, he’ll have more time to quickly react to fireballs coming his way.
More King Boo Attacks
This Slam attack can be avoided easily by staying in a corner. You’ll just have to pay attention to which King Boo emanates the ring. Luigi needs to jump over the ring to avoid it.
At one point during the later phases, the King Boos will throw a bunch of bombs. Don’t bother trying to vacuum these, as they have a short timer. You won’t have any room to shoot it.
Pay attention to the shadows as that is where the bombs will drop. Staying on the move is important — there aren’t many safe spots to remain stationary.
Return Fire
After a while, King Boo will toss a spiked ball that will produce bombs or debris. Suck up a bomb and then shoot it at King Boo.
Some of the bombs have a shorter timer than others — you don’t want to suck those up.  The shorter fuse bombs flash faster than the other ones.
When there are multiple King Boos, you have to shoot the bomb into the correct one. I haven’t been able find a way to determine the correct King Boo, so this may just come down to luck.
A commenter has provided this tip to distinguish the King Boos:Â “The real King Boo has a full row of teeth, the fake King Boos only have two.”
Once King Boo has fallen, have Luigi vacuum up the purple tongue. He’ll need help from Gooigi as well. Pull back until you are able to slam King Boo.
Luigi’s Mansion 3 Ending
After many attempts, Luigi finally captures King Boo. The Poltergust spits out the King Boo Gem. When this happens, the entire hotel collapses.
Luigi makes a flying leap for the painting that contains his friends.  Emerging from the rubble, Polterpup saves Luigi from the fall. Luigi pulls his friends out from the painting.
At the same time, Professor E. Gadd’s machine that holds all the ghosts that Luigi has collected so far — is cracked open. This releases all of the ghosts who then converge to take back the King Boo Gem.
But just before they recover it, the Gem disperses. The ghosts find themselves without a purpose, and are saddened at the sight of their home.
Professor E. Gadd makes the best of the situation by joining everyone to help rebuild the hotel.
The credits roll, with snapshots of the entire crew. With the hotel rebuilt, Luigi, Mario, Princess Peach and the Toads join the bus to return home.
What did you think of the Luigi’s Mansion 3 Ending? Is it even possible for King Boo to return? Leave a comment below.
The real King Boo has a full row of teeth, the fake King Boos only have two.
Thanks for the tip!