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

This card's effect reads, "Delete 1 of your opponent's Digimon with a play cost of 6 or less. If no Digimon was deleted by this effect..." How does this effect work, exactly?
"If no Digimon was deleted by this effect" refers to times where, when is activated, your opponent doesn't have a Digimon with a play cost of 6 or less in play, or an effect makes it so that there are no Digimon you can delete. Essentially, it means there was no Digimon in play that could be deleted by "Delete 1 of your opponent's Digimon with a play cost of 6 or less."
Ruled Mar 28, 2024
If my opponent has a Digimon with a play cost of 6 or less in play, can I activate this card's and choose not to delete my opponent's Digimon in order to trash the top card of their security stack?
No. If you use this card's and your opponent has a Digimon with a play cost of 6 or less, you must target that Digimon when you activate the effect. If a valid target exists, you must choose it as part of the effect.
Ruled Mar 28, 2024
My opponent has 2 Digimon in play with play costs of 6 or less. One of them has an effect that reads, "This Digimon can't be deleted by your opponent's effects," while the other does not. If I activate this card's , can I choose the Digimon that "can't be deleted by your opponent's effects" in order to trash the top card of my opponent's security stack?
Yes. Digimon with play costs of 6 or less are valid targets. If you choose it, the "can't be deleted by your opponent's effects" will prevent it from being deleted, allowing you to trash the top card of your opponent's security stack instead.
Ruled Mar 28, 2024
Got a line that uses MetalGarurumon? Map it in the builder and share it with a link.
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.