I have to make a ruling for, in what circumstances is a card no longer "that card." I need this because we can actually lose a card while still caring if it's "that card." In particular if it's shuffled into a deck we've lost it; so, a card shuffled into a deck is no longer "that card."
[...]
In practice we can totally know if we have the right card; and if we aren't sure which physical card is which that doesn't matter, I can say, "I take the one that's the same one" or "I take a different one." In these situations that never come up. But, shuffle it into a deck and man, we don't know and there's no way out (except now this ruling).
I love edge cases. I think this one says the decision you went with later is a good one, and the "it's no longer 'that card' when you shuffle" is incomplete. Here's the edge case:
I play a duration card, let's say
Fishing Village. I take it out of play and put it back into hand. Using
Secret Passage I put the Fishing Village somewhere in the middle of my deck without counting. Then I play
Scrying Pool, drawing cards up until roughly about where I put the Fishing Village. I play Vassal, hitting a Fishing Village.
Is it "that card"? Who the
knows...
The duct-tapiest workaround ever is to say that you either count where you put the Secret Passage card, or else what you're doing is a very limited form of shuffling, and so it's no longer "that card". What does that do to Stash?
Like I said, I like your later decision.