I'd say a mandatory Copper gain into hand is a bit of a wash, whether or not the card is an Attack card. Overall, you have a terminal Action that provides +$2 for $3. Still very weak.
You could try adding a +1 action to the card, so it's non-terminal. That way, it's functionally a silver that doesn't clog your hand, but has the nominal attack benefit of cluttering your opponent's hand with copper; the fact that they get to use the copper once before it becomes clutter helps it balance out.
It means that buying/using the Soup Kitchen early in the game might help your opponent more that hurt them, if that extra coin allows them to get some early 5-cost cards. Later in the game, it becomes much more powerful as an attack, since, accompanied by a draw engine, it could be spammed to muck up an opponent's engine. Would also synchronize well with hand-size attacks. The late game-effects might justify charging 4 instead of three for the card.
Thank you, i'll try that.
Thinking more about it, the more I think it's an interesting approach -- and the more I think $3 may be a better price, to encourage multiple buys and to make it a vialbe alternative to silver; early in the game, this is probably worse than a silver; late in the game, this is probably better than silver. And, unlike silver, this could TR/KC.
Many attack cards get weaker as the game progresses, but this one gets stronger. Late in the game, an extra copper in the opponents hand doesn't matter as much as it would early on, but the extra copper is increasingly inconvenient as it is likely to lower the average coin value of a deck upon reshuffle. Also, late game you're more likely to have an engine that can draw in the extra cards necessary to play this card.
Imagine KC-ing this or playing 3 or 4 in a single turn. You've probably guaranteed yourself -- and your opponent -- a Province buy. But next reshuffle, his deck is 3-4 coppers thicker, and your deck is just as lean as it was before.
The biggest drawback to this card is probably that I can quickly think of several cards who's presence would mean this card would be ignored (not that all cards don't have some version of that scenario)... with Gardens, you don't want to spam coppers into your opponent's deck. Same definitely goes for Counting House and, to a lesser degree, Coppersmith. That said, on most boards Counting House is so underpowered it gets ignored, so I don't think the conflict would really be that strong. And with Coppersmith, extra coppers is still likely to be a problem later on when it slows deck cycling -- and access to the Coppersmiths. The only real "problem" is gardens, but I think there are other cards that allow your opponents to gain cards and they aren't considered broken because the occurrence is fairly rare.
That said, if I can talk people into it, this is a card I'd have fun helping playtest to see if it works... good luck in finalizing your design.
