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

Is the card placed on top of my security stack by this card’s effect the Digimon played by my opponent or the card revealed from my hand?
The card revealed from your hand.
Ruled Mar 28, 2024
Can I activate this card's <Opp Turn> effect when [BT9-103]/[Kongou]'s effect is preventing cards from being added to my security stack?
You can activate the effect, but you can't add cards to your security stack, therefore the revealed card can't be added to your security stack and is trashed by the rules.
Ruled Mar 28, 2024
Can I use this card's <Opp Turn> effect to reveal [EX2-045]/[Calumon] from my hand when my opponent plays a Lv.- [EX2-045]/[Calumon]?
No, you can't. [EX2-045]/[Calumon] is a card with no level, so it isn't considered to have the same level even though it's the same card, and you can't use this card's effect to reveal it.
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.