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

Does this card’s <Start Your Turn> effect activate even when my opponent’s security stack is empty?
Yes, it does. While there are no cards in your opponent’s security stack to trash, you still perform the part of the effect that reads, “Trash the top card of this Digimon.”
Ruled Mar 28, 2024
When placing cards from my opponent's trash at the bottom of their deck with this card’s <When Digivolving> effect, who gets to decide the order of the cards?
The player who controls this card decides.
Ruled Mar 28, 2024
Does this card’s <When Digivolving> effect let me place Digi-Egg cards from my opponent's trash at the bottom of their deck?
Digi-Egg cards in your opponent’s trash can be chosen as part of the effect, but they’re returned to the bottom of your opponent’s Digi-Egg deck instead of their normal deck.
Ruled Mar 28, 2024
If there are 2 cards with [Mega] in their traits in this Digimon’s digivolution cards, do I get to place 20 cards from my opponent’s trash at the bottom of their deck with this card's <When Digivolving> effect?
No. Even if you have multiple cards with [Mega] in their traits, this effect will only place 10 cards from your opponent's trash at the bottom of their deck.
Ruled Mar 28, 2024
If my opponent has 9 or fewer cards in their trash, does this card’s <When Digivolving> effect still activate?
Yes, it does. Place as many cards as you can at the bottom of your opponent’s deck.
Ruled Mar 28, 2024
Can I choose not to activate this card’s <Start Your Turn> effect to avoid trashing any cards?
No, you can't. You must activate this effect at the start of your turn.
Ruled Mar 28, 2024
Does this card's <Start Your Turn> effect activate when this card has no digivolution cards?
No. When there are no digivolution cards, you can't perform "trash the top card of this Digimon," so it doesn't activate.
Ruled Mar 28, 2024
My turn starts when I have this card with [BT9-083]/[Omnimon: Merciful Mode] as its top digivolution card. If I use this card's <Start Your Turn> effect to trash this card, then activate the <Start Your Turn> effect on the [BT9-083]/[Omnimon: Merciful Mode] that was a digivolution card, can I trash a total of 2 cards from my opponent's security stack?
No. The <Start Your Turn> effect on the [BT9-083]/[Omnimon: Merciful Mode] that was a digivolution card isn't yet in a state where it can activate at the start of your turn, therefore it doesn't trigger.
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.