Hall of Armor
From the Super Mario Wiki, the Mario encyclopedia
The Hall of Armor is a location in Luigi's Mansion 3. It is found on the third level of the sixth floor, Castle MacFrights. It is north of the Front Gate and south of the Coliseum Balcony. The red gem can be found here.
There are two arches on either side of the room. The front two arches and the back left arch each have a suit of armor in front of them. The back right arch has an invisible suit of armor which Luigi can reveal using the Dark-Light Device. If Luigi destroys that suit of armor with the Suction Shot, he will get the red gem. At the end of the hall is the door leading to the Coliseum Balcony with a banner and a torch on either side.
Breaking the suits of armor with the Suction Shot reveals a large amount of money. There is a secret passage behind the back left suit of armor. In that secret passage is a treasure chest with a bunch of Gold Bars.
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