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

Can I digivolve into this card from a Digimon in my breeding area that has [Omnimon]?
No, you can't digivolve from a Digimon in your breeding area that has [Omnimon] using this card's effect.
Ruled Mar 28, 2024
I attack an opponent's Digimon with this Digimon, and use its <When Attacking> effect to delete the opposing Digimon. What happens to the attack?
The target of attack is no longer in play, so the attack ends without a battle.
Ruled Mar 28, 2024
I attack an opponent's Digimon with this Digimon, and use its <When Attacking> effect to delete the opposing Digimon. If this Digimon has <Piercing>, can I check the opponent's security cards?
No. You didn't delete the opponent's Digimon in battle, so <Piercing> doesn't activate.
Ruled Mar 28, 2024
My opponent attacks one of my Digimon with this Digimon, using its <When Attacking> effect to delete my Digimon. Can I use another Digimon with <Blocker> to block the attack?
Yes, you can. If you do, the blocking Digimon will battle this Digimon.
Ruled Mar 28, 2024
My opponent's Digimon attacks. Can this card's <Opp Turn> effect be used to to end the attack before the attacking Digimon's <When Attacking> effect activates?
No. This effect is activated at counter timing, which means it only activates after the <When Attacking> effect has finished activating.
Ruled Mar 28, 2024
My opponent's Digimon used a <When Attacking> effect to delete one of my Digimon with an <On Deletion> effect. If I use this card's <Opp Turn> effect to end the attack, does the <On Deletion> effect activate?
Yes. The <On Deletion> effect activates immediately after the deletion occurs, so it activates before this card's <Opp Turn> effect.
Ruled Mar 28, 2024
My opponent attacks with a Digimon. After activating my [BT1-082]/[Rosemon]'s effect, can I use this card's <Opp Turn> effect to end the attack?
Yes, you can.
Ruled Mar 28, 2024
My opponent attacks with a Digimon. After comparing DP in battle, can I activate this card's <Opp Turn> effect to end the attack?
No. The battle has already concluded, which means the counter timing window for activating the effect has passed, so you can't activate this effect.
Ruled Mar 28, 2024
If I use this card's <Opp Turn> effect, will the game treat the attack as if it never occurred?
No. <When Attacking> effects will activate as normal.
Ruled Mar 28, 2024
Can I digivolve one of my Digimon with [Omnimon] in the battle area into this card in the hand when an effect to digivolve one of my Digimon is activated?
Yes, you can.
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.