Book of Moon

Flipping a monster face-down will remove most "Lingering Effects" from it (except "change control" effects), EG:

• ATK changes from "Shrink", Gale, or "Card Trooper".
• The "Negate its effects" part of "Debris Dragon" or Vayu
• "But banish it if leaves the field" effects of "Plaguespreader Zombie" or "Battle Fader".

Flipping a monster face-down will sometimes cause a monster to "forget" things, EG:

• The fact that it was Summoned by a "Gladiator Beast"
• Whether or not it has used its "Once Per Turn" effect (except effects like "Des Lacooda"'s)
• Wheter or not it has been Gemini or Flip Summoned. A full list of these can be found here, under "Remembering": https://www.mikamika.de/edison-rules

When a card specifies "that target", and "that target" is "1 face-up monster", Setting it can save it. EG:

• Karma Cut: "target 1 face-up monster your opponent controls; banish that target". Since "that target" is "1 face-up monster", if it's flipped face-down by this card, it is NOT banished.
• Caius the Shadow Monarch: "Target 1 card on the field; banish that target" Since "that target" is "1 card on the field", if it's flipped face-down by this card, it IS banished.