I see what you're saying. Throne Room cares if it's "that card" but "loses track." The "lose track" isn't about this, and the words "lose track" aren't used anymore, the rule is about not moving cards; see below. However Throne Room does track the card, in that the card matters for whether or not Throne Room stays in play, and Throne Room does have to stop tracking the card once it leaves play.
First about "lose track"
Whether you call the rule "lose track" or "stop moving", it's still about both things: Abilities tracking cards, and not being able to move them. It's not just about the card being in the expected place at the moment the ability tries to move it. If that were the case, the ability could move a card that moved and moved back. It's actually about the ability tracking the card from the moment it references it, and if at any moment the card is not where it's expected to be, the ability loses track forever. It's crucial that it's thought of in terms of abilities tracking cards.
I see from your quoted rule that you're again missing this aspect. I pointed it out in the original "errata and rules tweaks" thread, and as a result you updated the rule with the added phrase
"or has moved away from there and then back". (I still think the rule is not phrased accurately, since it doesn't mention tracking.)
But if your intent is to change the rule (so that a card that moved back can actually be moved), then we don't necessarily need to think in terms of keeping track anymore. It's enough to look at where the card is when the ability tries to move it.
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When I talked about Thief tracking the card, I meant in terms of "lose track" (or "stop moving"). That's why it's not comparable to Graverobber. Thief can and must get the right card. Graverobber just gets an arbitrary card.
Sure, sometimes you know it's the same card. That doesn't stop me from having a rule that says it's not "that card."
I think it does if the rule is based on what I know (like you were arguing about my knowledge of how many cards I discarded etc) instead of game state. You said originally in this thread that the shuffled card is lost because "there's no way to know". Well, if it's the only one in my deck, I
do know. I assumed that you meant that "
potentially there's no way to know", just like
potentially a trashed card is unknown. But if it's all supposed to be,
do I know?, then I don't see how you can say that a shuffled card is always unknown.
You choose whether you want the same or a different Fishing Village in the trash, yes. And of course ideally the rules are such that that doesn't matter, it never makes a difference.
My point is that it does make a difference with this ruling. I choose which FV, so I choose whether Vassal gets discarded or not. Since you're saying that I can get that card because I know which one it is, then I can also choose to get another card.