Hôtel de la monnaie
You may reveal a Treasure card
from your hand. Gain a copy of it.
When you buy this, trash all Treasures you have in play.
When you buy this, you trash all of your Treasure cards in play. You do not trash Treasure cards in your hand or elsewhere; just the ones in play, if any. If you buy multiple cards in a turn, trash your Treasures right when you buy Mint; you still have any leftover coins they produced for spending on something else. Remember you do not have to play all of the Treasures from your hand each turn (just all the ones you want producing money for you). You do not get additional chances to play Treasure cards between buys in the Buy phase; first you play Treasures, then you buy cards. When you play Mint, you reveal a Treasure card from your hand and gain a copy of it from the Supply. The gained card goes into your discard pile. The revealed card stays in your hand. The Treasure card can also have other types, like Harem (from Dominion: Intrigue). If you buy a Mint and use Watchtower to put it on top of your deck or trash it, you still trash all of your Treasures from play. However, if you buy a Mint with Royal Seal in play, the Royal Seal will be gone before you can use it to put Mint on your deck.