Text: CONSTANT Once per Round, while this is in play, when your MC is defended, you can Stockpile 1. (Place the top card of your Main Deck into your Stockpile.)
FAQs/Rulings
Can multiples of the same card use a "Once per Round" effect?
No. “Once per Round” effects can only be used once each Round across all cards that share a name and tag.
If my Rival defends against my attack and I use a Response Support to remove that defender from the Combat Area, can I still trigger this effect?
Yes. As soon as your Rival defends your attack, this effect can trigger. This happens before any Response Supports can be used.