Without reading other posts...
Candlestick Maker -- Simple. Looks like a decent $2. Non-terminal, +Buy, and even a Coin token you can save. I like it. And of course, I like that Butcher, Baker and Candlestick Maker all have to do with coin tokens. The other two cards with Coin tokens are Plaza and Merchant Guild... if only the Plaza were a Tub.
Stonemason -- Stonemason is a $2 card, but I expect it will often be bought for more than that. It is actually really, really neat. When you overpay for it, you actually effectively get +$ equal to what you overpaid and you effectively get 2 buys to boot. Note that they don't have to be the same action card; they just need to be the same cost.
Question: Is it possible to overpay by $0? For the other overpay cards, it doesn't work because you get no benefit unless you overpay at least $1. But with Stonemason, you could still benefit if there are action cards costing $0, which is possible with cost reduction.
I expect that "overpay" requires paying at least $1, in which case you would have to be careful with cost reduction not to reduce the card you want to mason down to $0. Still, it could be a pretty powerful combo. With ONLY a Quarry in play, you could get Stonemason and two $4s. Cost reduction is doubly effective for Stonemason because it reduces the initial cost of Stonemason as well as the amount you need to overpay for any specific card.
Masterpiece -- I can't think of any realistic reasons why you would buy this for $3. At $3, Silver is strictly better. The only exception is when you want variety for some reason, but you'll want Silver anyway and it would be better to get this with an extra Silver for $4 rather than buying the Silver separately. Outside of Gardens games, you'll probably never buy this for less than $5. Even at $4 you will usually prefer having a Silver without an extra Copper. At $5, it is a decent deal: 2 Silvers with an extra Copper tossed in. Since overpay is on buy, you can still lose the Masterpiece to, for example, Trader. Masterpiece+Trader could be very silly, especially with Feodum (and Feodum+Trader is already silly).
Someone speculated on something very similar to this earlier, and I criticized it. I can't remember if it was exactly like this (in which case I was wrong) or if it was, like, a non-terminal +$2 action (in which case I stand by my original statement).
Advisor -- I quite like this card. I submitted a very simlar card to the non-attack interaction contest of the MSDC:
#2 (tie) - Artificer by eHalcyon with 13 points (Clementine)
$5 - Action
+5 Cards
+1 Action
Reveal your hand. The player to your left chooses a card to discard from your hand, then the player to your right does the same.
With Artificer, you get the worst 3 of 5; with Advisor you get the worst 2 of 3.
I like Advisor, but I think it will be weak unless you get a deck of super high quality, where no particular discard hurts you. It's big bonus is that it increases your hand size non-terminally. Decks that rely on key cards will not be able to use this effectively without other support (e.g. Cellar).
Plaza -- simple village variant for the theme. The Treasure discard is necessary so as not to make it superior to Bazaar. This may be a tricky card to use optimally. Villages want to be in engines. Many engines will want to trash away all the Coppers; discarding the few high quality treasures in the deck would not be worth just one coin token. But the drawback is ameliorated if you can draw the treasure back again.
Taxman -- the treasure discarder that fan card creators always think about! This one keeps the power reasonable through two checks:
- it only hits players with more than 4 cards in hand;
- you have to trash a copy of the treasure, so it hurts you to target non-Copper treasures.
If that were all that it did, then probably this would be nothing more than a Copper trasher most of the time. But it also has a delayed Mine effect, top-decking the gained treasure instead of putting it in your hand. Thus it is not strictly superior to Mine.
This should be a pretty good engine card, I think. Not sure. Well, you replace Coppers with more efficient treasures, at the same time slowing down your opponent, sometimes quite significantly. Making them discard Silver or Gold is pretty huge.
Merchant Guild -- On its own, this is sort of a restricted terminal Gold. You get 2 buys, which means you can get up to 2 coin tokens. But you can't spend those coin tokens until the next turn. Maybe Merchant Ship is comparable in this respect? And like Goons, multiple MGs can get you a massive coin token surplus. Interestingly, that means that you could potentially play to a MG megaturn strategy.
It would be more difficult than with Goons though. With the latter, you go out in one giant blaze of glory, racking up huge points and draining 3 piles, probably massively lowering the quality of your deck by filling it with Coppers or Curses. With MG, you can't exactly do that because the MG megaturn only gets you a crapton of money, not VP. You then have to use the money... probably over the next several turns, putting together as much +Buy as you can to make use of all the coin tokens you now have. Watchtower makes it easier.
But yeah, I don't think MG will be all that effective unless you play multiples together, and/or have another reason to use every buy (Gardens, Watchtower, maybe Trader).
Soothsayer -- This is disappointing to me, because I don't think it really fits the theme of the expansion. No coin tokens, no overpaying. In every other expansion, the curser exemplified the theme.
Seems decent, not great. Gaining Gold is nice, but it doesn't help you at all on the turn you play it AND it helps your opponents. Interestingly, this is like Marauder's big brother. Gain Gold vs. Spoils, opponents gain Curse vs. Ruins. But I think Marauder is stronger because it doesn't help opponents when you play it, and you can always open with Marauder.