"While Arya Stark has a duplicate, she gains a [military] icon.

Reaction: After Arya Stark enters play, place the top card on your deck on her facedown as a duplicate."

What happens to this facedown card after this? Is the cost of Arya that you lose another card every time she enters play to act as a duplicate and give her a military icon? Does this card stay with her until she's killed or discarded, and then discarded?

Thanks again!

The card is used as a Duplicate so it goes to the discard pile.

What happens to this facedown card after this? Is the cost of Arya that you lose another card every time she enters play to act as a duplicate and give her a military icon ? Does this card stay with her until she's killed or discarded, and then discarded?

I'm a little confused by that highlighted statement. How many times is Arya entering play during a game?

Plus, you know, if you really don't want to lose the card, you can always choose not to trigger the Reaction.

The facedown card acts like a duplicate, so it follows all the regular rules for duplicates, namely:

1. It stays in play on the original card.

2. It can be discarded to save the original card from leaving play (i.e., being killed, discarded, returned to hand, etc.).

3. If the original card leaves play without it dupe being used to save it, the dupe is discarded.

Gotcha! Now I understand. Thanks for the responses! I only use one deck, so I'm not as familiar with the duplicates rules. =)

Is the cost of Arya that you lose another card every time she enters play to act as a duplicate and give her a military icon?

One thing I would also point out is that "lose a card" is kind of the wrong way to think about it. Similar to cards you lose with Pillage: functionally, those cards could have been on the bottom of your deck so that you'd never see them in the course of the game. A shuffle could have easily left them in a position where you'll never draw into them.

Would you describe it as "lose a card" if Arya's text said "place the bottom card of your deck on her facedown?" or "shuffle your deck and place a random card"?

Just food for thought =)

Well, decking is a loss condition (an unlikely one, granted), so regardless of where in the deck the card comes from, you're losing a card to Pillage. In Arya's case, however, you get to use the card as a duplicate on Arya, so you're not losing it (still regardless of where in the deck it comes from).