If I have a Digimon card in my trash with a level that's different from all of my opponent's Digimon, can I use this card's [When Attacking] effect to return that card to the bottom of the deck?
Yes, you can.
Mar. 28, 2024
If I use this card's [When Attacking] effect to return a Digimon card with no level to the bottom of the deck, can I delete my opponent's Digimon with no level?
No, you can't. Digimon without a level can't be targeted by effects that reference levels.
Mar. 28, 2024
If an opponent's Digimon enters the battle area after this card's [When Digivolving] effect activates, does that Digimon gain "[When Attacking] Lose 4 memory"?
Yes, it does. This card's effect targets "all of their Digimon," therefore opponent's Digimon that later enter the battle area are also affected by this effect.
Mar. 28, 2024
