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

What does “Choose any number of your opponent's Digimon whose play costs add up to 15 or less” mean, exactly?
You can choose any number of your opponent's Digimon, as long as the play costs of the chosen Digimon add up to 15 or less. For example, you could choose 1 Digimon with a play cost of 3 and 1 Digimon with a play cost of 12, or 1 Digimon with a play cost of 2 and 2 Digimon with play costs of 6.
Ruled Mar 28, 2024
Can I choose fewer cards than possible, even if the play costs of the chosen cards add up to less than 15?
Yes. As long as the total play costs of the chosen cards is less than 15, you can choose as many or as few cards as you like. However, note that you must choose a minimum of 1 Digimon with a play cost of 15 or less.
Ruled Mar 28, 2024
My opponent uses effects to reduce play costs or play Digimon for free. Are Digimon played with these effects counted as having reduced play costs or play costs of 0 by this effect?
No. Regardless of how a Digimon was played, only the play cost printed on the card is counted for this card’s effect.
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.