Ug has been cleaned off the floor 9 of Luigi's Mansion 3, we will be able to venture into the damp corridors of the second basement boiler room. It starts with the elimination of a few recalcitrant ghosts, while boss of the area is already starting to create some pitfalls in your path. First, take care of the ghosts and see how to open the door: a fake wall closes a sewer plate, right next to the one that is already visible. Pull the sheet and make Gooigi go inside the pipe to get the key.
In the next room, pass Gooigi through the tube to the level below. The goal will be to prevent him from getting wet. Take a good look at the illuminated parts of the valves and reproduce what you see in the series of images below:
Dock on the nearby ledge and take Gooigi out so he can pass through the pipes. The second one will lead you to the yellow end chain that will open the gate for Luigi and his buoy. Next room, same principle, with one exception: Luigi will first have to move the valve at the end of the room, and from his buoy, to cut the water flow that is hindering Gooigi's progress. Once Gooigi has passed, all you have to do is pull on the other rope so that the current can carry the buoy away.
Luigi is being carried straight to a wall full of spikes. Stay on Gooigi no matter what happens and pass it from pipe to pipe until you reach the end of the room, near the gate. Pull the rope and stay on it until Luigi can pass without obstruction. You should have plenty of time to do this sewer sequence before the plumber gets his buoy blown up on the opposite wall, the trick is not to change characters in the middle. Stay focused on Gooigi and nobody else.
New series of pipes to avoid for Gooigi: wait for the right time to pass. Then go back to Luigi to pull the rope blocking the water supply preventing Gooigi from progressing. After a larger series of pipes to dodge, Gooigi will then be able to pull and hang a chain, too. This one will release shark fins which, if they hit Luigi, will sink him directly. The trick is to get them around the big buoy placed near the grid. Once they're gone on one side, vacuum all the way to the exit!
The lever to lower the water level is within your reach, but a new puzzle with valves comes to spoil the party. As before, we will offer you a series of images showing the correct position of the valves so that you can reach the switch as quickly as possible with Gooigi. Once the water level has dropped, you can descend the ladder and walk into the freshly emptied pool, so all you have to do is back up and kick the boss' ass.
Some small fights will slow you down and a chest will also come alive to try to eat you. The solution: take any object at the end of your vacuum, then throw it on it to stun it, a small blow of Dark-Light Device and the chest is done for. Return to the central room and take the door that separates you from the boss.
Floor B2: Boiler Room Boss
The boss will recreate a pool, so jump into your buoy. Stay away, while we examine a little bit all the types of attacks he is likely to throw. When he makes his circular attack, he ends up dizzy.
Go grab the tip of his buoy, then blow it on the spikes, if possible near the ladder. It will give you time to dock, flash the man and aspire as many life points as possible. There's no strange phases during the fight, just faster attacks.