Emotional Upset [single]

[The Dark Knight]

Emotional Upset
|Spell/Continuous|
Oncer per turn, during your Standby Phase select 1 face-up card on your side of the field and your opponent selects 1 face-up card on their side of the field. Flip the selected cards face-down. They cannot be flipped face-up and cannot be removed from the field as long as this card remains face-up on the field. If a player cannot select a face-up card on their side of the field to flip face-down, reveal their hand to their opponent and their opponent selects 1 card from the revealed cards. Banish that card. It is not affected by card effects for the remainder of the duel.

Idk. Just felt like making a card.

[Demon Loki]

Pretty unique.
It's like a "Book of Moon" with a side-effect.
Well done.