Red Moon Monastery

Red Moon Monastery is an anomalous level found in certain personalized copies of Super Mario 64. It is typically found in an anomalous part of the castle known as the Lunar Tower, although the method of unlocking the tower can vary. The stage itself resembles an alternate version of Big Boo's Haunt, which leads some to believe the stage was cut due to being too similar. The stage is most well-known for having a large, red moon in the skybox, which is where the name comes from. It is also known for having an ever-present red tint and prominently featuring the Red Boo instance of Enemy Discoloring, nicknamed "Hypno Boo", and Dry Bones in the catacomb subarea. Music tracks for this level and it's main boss fight have been found, and they can be listened to here, here and here.

Geography
The stage is described as a church-like building in the center of a sizeable forest, with most of the stage taking place in the building filled with red Boos, Dry Bones, and Mr. Is. Under the main part of the monastery, there is a basement that holds most of the Boos, which are usually reported to reveal a star when they're all defeated. The basement has an entry to a subarea, being a catacomb, which holds many of the anomalous Dry Bones enemy. Players commonly report finding a key in the catacombs on the course's fifth mission, commonly unlocking the area leading up to the level's main boss fight, commonly described as a series of hallways, slopes, and trap doors eventually leading up to the room containing the boss fight arena.

Missions
Red Moon Monastery has had many missions reported, but the most commonly mentioned star, nicknamed "OVER THE CHANCEL" can be found floating in the first room of the monastery itself.

Another star is reportedly found by defeating a certain number of Boos in the basement, which can either spawn the mission's star or a Big Boo that must be defeated to complete the mission. This Big Boo can also reportedly have the same properties as a "Hypno Boo", and even unlock the catacomb subarea of RMM.

Other reports talk about using a key to unlock a locked room with a star in it, breaking a box in the catacombs that contains the star or multiple boxes containing 8 red coins, using a Vanish Cap to phase through the stained glass seen on the monastery or a cage in a part of the map, and fighting a unique miniboss that appears as a flying, robed cultist with a Shy Guy mask that throws fireballs at the player. A notable aspect of this miniboss is that when defeated, some claim that it references the level's main boss being some sort of manifestion of the red moon, before dropping a key to the part of the level leading up to a fight with this level's boss, the Spectral Scourge.

Most commonly described as a large blue fire with a face on it resembling the fire seen in the painting of Lethal Lava Land and retextured Eyerok hands that it uses to attack the player. It has been said that it also has the ability to summon Amps, or spit fire at the player. It reportedly has to be summoned with a "ritual" by lighting multiple torches, either by pressing switches or using an anomalous power-up like the Fire Flower.