3 official rulings from Bandai, last ruled Sep 6, 2024. Straight answers to how this card actually resolves.

Can I use this card's <Main Timing> effect to pay 3 cost even when I don't have any [Legend-Arms] or level 6 Digimon?
No, you can't. The activation conditions include paying 3 cost and placing this card as 1 of your [Legend-Arms] or 1 of your level 6 Digimon's bottom digivolution card, therefore the effect can't be activated just by paying 3 cost.
Ruled Sep 6, 2024
Can I use a Digimon that was played this turn or a suspended Digimon to attack with this card's <When Digivolving> effect?
No, you can't. This effect does not allow you to attack with Digimon that are in a state where they can't attack.
Ruled Sep 6, 2024
If a [RagnaLoardmon] with this card in digivolution cards is deleted in battle against a Security Digimon, does that Security Digimon's <Security> effect activate?
No, it doesn’t activate. The activation timing for the <Security> effect is before the battle with the Security Digimon, so even if a [RagnaLoardmon] with this card in its digivolution cards is deleted in battle, the <Security> effect can't be activated.
Ruled Sep 6, 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.