Book of Moon
Edison Card Text
① Target 1 face-up monster; Set it.
Targets
No Damage Step effect
Banlist • Unlimited
Interactions
What happens if Embodiment of Apophis is set face-down?✓
Book of Moon is used on Embodiment of Apophis.
It becomes Set in its corresponding Spell/Trap Zone as a Trap Card.
If Absolute Zero is set with Book of Moon and then Noblemanned, does it trigger?✓
Absolute Zero is face-down and removed by Nobleman of Crossout.
No. Absolute Zero must leave the field face-up to trigger its effect.
Rulings
edisonformat.net
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.
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.
● Paleozoic Dinomischus: Target 1 face-up card on the field; ...banish it."
Since this card banishes "it", it IS banished (this card is not legal in Edison, but is a good example).
edisonformat.com
Flip 1 face-up monster on the field into face-down Defense Position.
This effect targets 1 face-up monster.
A monster flipped face-down remembers:
if its Battle Position was changed this turn.
that it declared an attack this turn.
that it was Normal / Flip / Tribute / Ritual / Fusion / Synchro / Special Summoned.
on what turn it was Summoned.
which Synchro / Fusion / Ritual Material Monsters were used for its Summon.
A monster flipped face-down forgets:
the properties of cards used for its Summon (name, Attribute, Type, etc.).
what method / effect Summoned it (ex: "Exodius the Ultimate Forbidden Lord").
where it was Summoned from.
lingering effects that previously applies to it (like "Limited Removal").
if it used its "once per turn" effect(s) earlier this turn (read about exceptions [HERE]).
if it was Normal Summoned again (in the case of Gemini Monsters).
if it had been Flip Summoned.
You cannot flip a Monster Token face-down because Monster Tokens are always face-up.
You cannot activate "Book of Moon" while "Light of Intervention" is active.
This card cannot be activated during the Damage Step.