A Digimon with a play cost of 9 or less attacked a player, digivolved using a ＜When Attacking＞ effect, and became a Digimon with a play cost of 10 or more in a state where this card's ＜On Play＞＜When Digivolving＞ effect was activated for my opponent. What happens to the attack in such cases?

The attack has already been declared, so the attack will continue.

Alphamon rulings (BT13-075)

2 official rulings from Bandai, last ruled Mar 28, 2024. Straight answers to how this card actually resolves.

Effect: [On Play] [When Digivolving] By placing 1 Digimon card with the [X Antibody] trait or the [Royal Knight] trait from your trash under this Digimon as its bottom digivolution card, all of your opponent's Digimon with a play cost of 10 or higher can't attack players until the end of your opponent's turn. [All Turns] [Once Per Turn] When this Digimon would leave the battle area by an effect, by returning 1 Digimon card with the [X Antibody] trait or the [Royal Knight] trait from this Digimon's digivolution cards to the bottom of your deck, prevent it from leaving play.

Official Q&A

When my opponent activated this card's ＜On Play＞＜When Digivolving＞ effect, my Digimon with a play cost of 9 or less digivolved in my next turn and became a Digimon with a play cost of 10 or more. Can I attack with this Digimon?
No, you can't.
Ruled Mar 28, 2024
A Digimon with a play cost of 9 or less attacked a player, digivolved using a ＜When Attacking＞ effect, and became a Digimon with a play cost of 10 or more in a state where this card's ＜On Play＞＜When Digivolving＞ effect was activated for my opponent. What happens to the attack in such cases?
The attack has already been declared, so the attack will continue.
Ruled Mar 28, 2024

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Questions and answers are Bandai's official rulings, collected and translated by the DigimonCardGame Wiki community and reused here under CC BY-SA. Card names and card text are © their respective publishers; Combalo is not affiliated with Bandai.

Alphamon rulings (BT13-075)

2 official rulings from Bandai, last ruled Mar 28, 2024. Straight answers to how this card actually resolves.

Effect: [On Play] [When Digivolving] By placing 1 Digimon card with the [X Antibody] trait or the [Royal Knight] trait from your trash under this Digimon as its bottom digivolution card, all of your opponent's Digimon with a play cost of 10 or higher can't attack players until the end of your opponent's turn. [All Turns] [Once Per Turn] When this Digimon would leave the battle area by an effect, by returning 1 Digimon card with the [X Antibody] trait or the [Royal Knight] trait from this Digimon's digivolution cards to the bottom of your deck, prevent it from leaving play.

Official Q&A

When my opponent activated this card's ＜On Play＞＜When Digivolving＞ effect, my Digimon with a play cost of 9 or less digivolved in my next turn and became a Digimon with a play cost of 10 or more. Can I attack with this Digimon?
No, you can't.
Ruled Mar 28, 2024
A Digimon with a play cost of 9 or less attacked a player, digivolved using a ＜When Attacking＞ effect, and became a Digimon with a play cost of 10 or more in a state where this card's ＜On Play＞＜When Digivolving＞ effect was activated for my opponent. What happens to the attack in such cases?
The attack has already been declared, so the attack will continue.
Ruled Mar 28, 2024

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