JUDGEMENTThank you everyone for your entries and for your patience. There were a lot of great submissions, and as always, judging isn't easy! I wish I had the time to playtest the cards, but unfortunately I had to rely mainly on initial impressions. Anyway, without any further ado, here are my comments:
Aquila's HollowHollow can function as either a draw-to-X card or an Artificer-like gainer, and can be played immediately or as a duration. The draw-to-X ability when played as a duration makes it a strong counter to handsize attacks, and otherwise functions like a non-cantrip Caravan. The discard-for-benefit ability is watered down compared to Artificer, and playing it as a Duration for the purpose of gaining a card will often be suboptimal unless you have spammable cheap cards in the Kingdom. However, if you are able to play two or them (or throne one), the two functions of the card synergize quite beautifully. Interestingly, Hollow can pretty much guarantee that you are able to gain a $5-cost card in your next turn (barring any handsize attacks), so it could be useful for that purpose early in the game (although you would much rather see this on Turn 3 than Turn 4) or in a slog where being able to afford even a Duchy isn't always a given late in the game. I like the versatility of the card and with the right support, this can become fairly powerful.
mandioca15's ClairvoyantClairvoyant lets you gain a $5-cost card at the cost of either discarding a Treasure from your hand or receiving the next Hex. In many decks, discarding a Treasure from hand will be a minor price to pay for being able to gain a $5-cost card, especially relative to receiving a Hex mid-turn, which can be quite brutal in some cases. There will be times when the choice of which penalty to take will be more interesting, but I would wager that more often than not the right choice will be fairly automatic and somewhat less interesting.
JW's GalaGala is an Action card version of Bargain (if you choose to gain a $5-cost card) the first time it is played in a turn, whereas for subsequent plays it becomes a vanilla Workshop. With the once-per-turn limitation and tried and true penalty of giving your opponent a Horse, the card seems balanced. Bargain itself is rarely bought more than once per game in my experience, but there are obviously advantages to gaining a $5-cost card during your Action phase rather than in your buy phase, so I would expect players to use Gala's ability to gain a $5-cost card fairly often.
Gubump's Larder *Short-List*Larder makes use of the Journey token to alternate between gaining cards costing up to $3 and cards up to $5. It's a clever use of the Journey token and I like that this costs the same as Workshop. There will be certain Kingdoms where this will be much better than Workshop, but in others you may run the risk of adding cheap cards that your deck doesn't want. I like the simplicity and elegance of the card.
Xen3k's Royal FoundriesRoyal Foundries is a powerful $7-cost non-terminal gainer that let's you discard a card to gain a cheaper card to hand. Ideally one would discard Colonies or Provinces but even discarding your expensive Actions or Treasures might not be much of a drawback if you can draw back around to them. I prefer the revised version to the original one that self-trashed if it gained a card costing more than itself. The card will be very strong, and in the greening phase you could even use Royal Foundries to gain and play more Royal Foundries. While it's definitely very strong, like with King's Court and Forge, Royal Foundries can whiff if you can't get it to collide with the right cards; while it's a card you probably want in your deck, the timing of when to buy one matters. I think the decision of when you start to green (as opposed to just buying more Royal Foundries) could also be interesting.
AJL828's FurnaceFurnace has an interesting concept whereby it allows you to reveal and discard any number of different named cards from your hand to gain a card costing up to $1 per card discarded. It's relatively cheap compared to Artificer, but your deck would require quite a bit of work for it to function well as a gainer. Games with Shelters or Heirlooms might make this more appealing early in the game, but I think on a lot of boards there will be more reliable gainers and unlike Artificer which also gives you some economy, Furnace doesn't do much else for you. I think it could even work at $2 as-is.
xyz123's KitchenKitchen has similarities to Butcher in that it allows you to spend Coffers to gain cards. The gaining is not contingent on trashing a card from your hand and so if you don't spend any Coffers you are forced to gain a $0-cost card. I think the wording is a bit ambiguous since it could be misinterpreted as allowing you to gain multiple cards, each costing up to $2 per Coffer removed, rather than a single card costing up to $2 per Coffer removed. This is an interesting twist on Workshop, and I like that it essentially forces you to spend Coffers if you don't want to junk your deck, because otherwise there would be a risk of this being too monolithic. I'm not entirely sure about the balance of essentially doubling the value of your Coffers when playing Kitchen, as there are definitely strong synergies with other cards that give you Coffers. Even the lowly Candlestick Maker can combo with Kitchen to let you gain expensive cards, and Kitchen could be quite potent in a Merchant Guild deck.
LastFootNote's Mill Town *Short-List*Mill Town is a village that lets you play Treasures from your hand to gain a card costing up to $1 per Treasure played. Playing Treasures during your Action phase could lead to some cool, sometimes funky, interactions as we've seen with Black Market and Storyteller, and Mill Town would be a great enabler of draw-to-X engines. In fact, for me this would be the main appeal of the card rather than its gaining ability. Since the cost of the gained card is based on the number of Treasures played rather than the value of those Treasures, building a deck around Mill Towns could be awkward especially in a weak Kingdom. Keeping a bunch of Coppers in your deck will make you more likely to dud, although if you aren't planning to gain Provinces with this, then you can still get by with some Copper-thinning. You still get to spend the coin from your Treasures in your Buy phase, but you will have less ammo for any subsequent Mill Town plays. Moreover, it will be hard to make good use of Mill Town's gaining ability until you get your engine humming (especially if this the only village in the Kingdom), since you generally want to play your villages before any terminal draw cards to find more Mill Towns and Treasures.
4est's Prized Hog *Short-List*This is a cheap cantrip that won't do much for you early in the game, but once your deck has more nice stuff in it, you are more likely to reveal something useful that you would be happy to trade your Prized Hog in for. Prized Hog could really shine as a gainer in a Kingdom with deck inspectors like Cartographers or Apothecaries, but I think this would be a fun card in any Kingdom. I like that the card self-trashes when you choose to gain a card with it, as otherwise there would be the potential for it to snowball if one player gets lucky with some good hits early on. I also like the flavour of the card (mmm....bacon).
NoMoreFun's Matryoshka *Short-List*Matryoshka is a neat $6-cost card that lets you gain a card costing up to $5, and then a card costing up to $4 that shares no types with it. In many Kingdoms, this probably means that you will opt for an Action card and a Silver in the building phase and perhaps a Duchy and something else in the greening phase. Too many silvers often are not ideal for your deck if you are trying to build an engine, but it may be a relatively small price to pay for gaining a card costing up to $5 (it's not clear to me if this is a worse "penalty" than topdecking a card with Artisan). That said, there will be boards that will allow you to gain both Action cards and useful Night cards or Kingdom Treasures, where Matryoshka will be especially strong and getting one in your deck early would help accelerate it significantly.
emtzalex's DeployDeploy is a $7-cost Event that let's you gain and Queue a card costing up to $5. Queuing is a fan mechanic similar to Exiling, except that you can add one card from your Queue to your hand at the start of your turn. Deploy could have been even more simply worded to say "Queue a card costing up to $5", but I prefer the submitted version since it triggers any on-gain effects while still using a small amount of text. The Event is reminiscent of Summon, except it works for $5-cost cards and provides you with a lot more flexibility since you are not required to play it at the start of your turn. One minor downside relative to Summon is that Deploy cannot act as a village, which can sometimes be a useful feature of Summon in Kingdoms without bona fide villages. A bigger limitation is that buying Deploy multiple times in a turn will not allow you to see the Deployed card in your hand at the start of your next turn because of the way the Queue mechanic works, whereas this limitation does not apply to Summon or Reap. I did wonder about whether Deploy should cost more than Reap, but perhaps the latter limitation justifies having them at the same cost.
spheremonk's FeteFete is meant to be used in place of an official Prize, and is essentially an enhanced Wish, which let's you gain two cards costing up to $6, one of which you gain to hand. Fete is a one-shot, as it get's placed on your Island Mat the first time it is played. How good Fete is relative to official Prizes like Followers or Trusty Steed will of course be situational, although on average I think it would probably be one of the weaker Prizes due to its one-shot nature (although probably strictly better than just gaining a Duchy if your opponent doesn't reveal a Province). It's an interesting idea (and I don't recall if there has already been a contest for designing a Prize but that could be fun), but I'm not sure if including this as a potential Prize really incentivizes you to go for Tournaments (you're probably doing so for Followers or Trusty Steed, or Princess if there is no other +Buy). On the other hand, this is arguably less swingy then some of the official Prizes, which some players might prefer.
faust's MonkMonk is an interesting card that lets you can trash a card from hand, and if there are no copies of it in the trash, you can gain a card costing up to $5. If there are copies of it, you get to trash another card from hand. It's quite a strong card in the opening, as both a decent trasher and allowing you to gain at least one $5-cost card unless you get unlucky. As with most trashers, the utility of the card will dwindle over the course of the game and once you run out of uniques to trash you will no longer be able to use it as a gainer. There are scenarios where shuffle luck could turn players off Monk e.g. one player is able to trash a Copper with Monk and gain a $5-cost card, while their opponent then draws Monk in a hand with 4 Coppers (although the consolation would be getting to trash an extra Copper). You could also have rare scenarios where one player gets an Estate and Copper trash before the other even if they both open with Monk. To be fair, you can get nightmare draws with official cards as well (e.g. opening with Baron and not getting it to collide with an Estate). However, I think it will feel worse with Monk since you are almost forced to go for it if your opponent does (or if you think they will go for it). There may be boards with stronger openings where you could possibly skip or delay Monk, but I think those would be in the minority.
grep's Trapper *Short-List*Trapper is a non-terminal, Night gainer that lets you gain cards costing up to $5 and also lets you topdeck them if you wish. The catch is that it only lets you gain cards that you don't already have in play (including itself), so it's ideal for strategies that want a variety of different cards in your deck. Nevertheless, Trapper would be quite strong early in the game and looks like a great option as a first $5. At worst, you can still gain Duchies with during the greening phase.
X-tra's Staircase *Short-List*Boom! Another $10-cost Event that allows you to add a bunch of stuff to your deck. It gives you more flexibility than with Populate (although the degree of flexibility will vary in each Kingdom), and could potentially add less junk to your deck relative to Alliance (although it generally won't score you as much points). While reminiscent of the other official $10-cost Events, I think this is different enough and moreover gives you a bit more to think about. I like it!
spineflu's BribeBribe is an interesting card that requires you to trash it along with a Gold from your hand to gain 2 differently named cards from the Supply. If you can't or don't want to trash it and a Gold for the gaining ability, then Bribe reduces the cost of Gold, so there is a nice self-synergy there. Bribe lets you gain any 2 differently named cards regardless of cost (including Colony, Possession, City Quarter, or a revealed Fortune), so the potential payoff could be huge. Like with cards like Treasure Map, it's probably best to have some deck control before plopping Bribes into your deck, which would mitigate the luck factor. Where deck control is not possible (or if you don't have gold gainers in the Kingdom), I could see this sometimes being quite swingy even with the consolation of making Gold cheaper.
LibraryAdventurer's BronzeworksBronzeworks lets you gain a card costing up to $5, and if it happens to be an Action, Bronzeworks becomes non-terminal and you get to topdeck that Action. Bronzeworks also has an interesting twist whereby you can gain a Curse for 3VP. All other types of cards are gained to hand, which can be quite useful when you need Treasures as payload or if you want to gain a Victory card and are able to Exile it or place it on your Island mat right away. I think this looks quite good compared to Artisan for gaining Actions even if they aren't gained to hand; because of the non-terminal nature you could still draw any Action that you topdeck (and sometimes with Artisan you need to topdeck the gained card anyway). You would need to be wary of Curse pile-outs in games with Bronzeworks (with a net gain of 2VP, they will score more than Estates) - especially if there are any throne room variants around - even if you have a decent points lead, which I think is a unique dimension that Bronzeworks brings.
Chappy7's BingeBinge is a cheap $2-cost Event that lets you gain a card costing up to $5 at the expense of gaining a Copper onto your deck as well as Exiling a Curse if the gained card costs $5. It comes with a necessary (IMO) once-per-turn limitation that prevents you from simultaneously emptying Duchies and Curses if you have at least $16 and 8 Buys. You can't do the same Watchtower trick as you can with Banquet as you still need to Exile a Curse, but other than that I think this looks quite good compared to Banquet because arguably adding an extra Copper to your deck is worse than Exiling a Curse when building. Moreover, any cost reduction would provide a fairly trivial loophole to prevent Exiling Curses.
Mahowrath's Hostage Taker *Short-List*Hostage Taker is a unique Reserve card which lets you call it when you shuffle your deck to gain a card costing up to $6 to the bottom of your deck. I think there may be an FAQ required to address whether or not you can "shuffle" a deck that contains no cards or only 1 card, but rules ambiguities aside, I like the premise of the card. The gaining of the card is delayed early in the game, but with sufficient thinning or draw, the frequency at which you can call Hostage taker will accelerate and will eventually allow for gain and play which I think would be fun to build towards.
Firestix's Parole OfficerParole Officer lets you Exile a carding costing less than itself when you buy it, and comes with a cool on-play ability that lets you play an Action card that you have in Exile twice. It looks fun, but I think it's too strong even if you don't have other ways of getting Action cards into Exile. Unlike other Throne Room variants, Parole Officer doesn't have the risk of whiffing, as long as you don't shoot yourself in the foot by somehow discarding your Action cards from Exile. I feel like the first person to hit $6 and essentially get a double-Mountebank, for instance, into their deck will have a huge advantage over their opponent. I would recommend a version that doesn't return the played card to Exile (you could consider giving Parole Officer an on-play ability to Exile cards).
The Alchemist's Spinster *Short-List*Spinster is an elegant card that let's you gain a card costing up to $5. It's non-terminal if the gained card costs $4 or less and if the gained card costs $3 or less it is a cantrip gainer. I think the card offers some interesting choices of what to gain. I do have a slight concern about making games lean towards rushes since you could gain a bunch of Spinsters and then start rushing down the Duchies, but I don't think it would necessarily be scripted.
MochaMoko's Master MerchantMaster Merchant has an interesting concept whereby you can set aside a card from your hand and then at the start of each subsequent turn, you put the set-aside card in hand and gain a card costing exactly $1 more, setting that card aside and then you rinse and repeat. The chain will be broken if there are no cards that can be gained by it, but on some boards it will be possible to trade your way up to Provinces or Platinums. While gaining expensive cards will be a slow process, Master Merchant increases your starting handsize for as long as Master Merchant stays in play (which on most boards can be for at least 4 subsequent turns if you set aside an Estate with it). There will be boards where Master Merchant might not be ideal, but overall it looks like the payoff could be worth it. In the greening phase, being able to Haven Duchies to gain a Gold (or Province for Platinum) to hand two turns later could also be useful in some situations.
exfret's Down Payment Down Payment lets you gain a card costing up to $6 if you can discard an Action or Treasure other than a Copper from your hand. It's tempting in the opening, especially in games with Shelters or Heirlooms, but can be risky if you don't get it to collide with the right cards. It would be safer to gain Down Payments once you have more deck control and more stuff in your deck, since it will then become quite strong (and obviously combos well with Village Green) since you could still draw back around to the discarded card. Down Payment also mitigates the risk of being slightly over-terminalled since you could then discard any Action cards that you wouldn't be able to play without any qualms.
RESULTS:
Runners-up:
Mahowrath's Hostage Taker
X-tra's Staircase
Winner:
4est's Prized Hog
Congrats 4est!