So I'll talk about half of these cards now and half later. I'll start with the second half because I suspect they tend to get overlooked by people who started at the top and are now running out of patience towards the end. Plus, I have a point about Sultan specifically that I want to make. I'll do the first half later.
Sultan
Types: Action
Cost: $5
+2 Cards. +1 Action. Discard a card.
When you gain this, look at the top 3 cards of your deck. Discard any number of them and put the rest back in any order.
The top half is probably too strong for $4 (I think someone mentioned that Donald X. playtested a version at $4 and found it too strong?) and almost (e.g. tunnel) strictly weaker than Lab at $5. But still maybe an ok $5 if Lab didn't exist.
So, one concern to think about with on-gains is: what if I open with it? Nomad Camp and Inn both mess with the opening split in different ways. IGG and Noble Brigand mess with your opponents. Farmlands is too expensive. I'm probably missing some others, but the trend is clear: if they mess with your opening split, they have fairly weak on-play effects (sure I can maybe get a 4/5 split with Nomad camp, but only if I commit to using an opening $4 on Woodcutter, and even then it's not likely; Inn is similar). Opening Sultan? I'm discarding at least one estate (and frankly, I'm likely discarding all of them to get an earlier reshuffle) and thus likely getting at least a $4.5/$4 opening, which is probably too strong?
Safe House
Types: Victory – Reaction
Cost: $3
Worth 2 VP.
When you gain a card costing $0, you may discard this. If you do, gain a Gold.
So, similar to Cache (instead of 2 coppers and a Gold, you get a copper, a gold, and a Victory card), but you have to spend an extra buy and can stack oddly. I'll have to think about it.
Commander
Types: Victory
Cost: $5
Worth 2 VP
When you gain this, gain a Reinforcement card, putting it on top of your deck.
Setup: Add an extra Action Kingdom card pile costing $5 to the Supply. Cards from that pile are Reinforcement cards and cannot be bought.
Clarification: Unlike most Victory cards, there are always 10 copies of Commander in the Supply regardless of the number of players.
Instead of IGG emptying IGG and Curse piles, this empties the Reinforcement and Commander piles simultaneously. On the other hand, a VP card doesn't help buy more Commanders, so rushing will be difficult, unless the Reinforcement card is something like Vault. I'd probably like this more if it were a half-Harem (1VP-$1) instead, but it might be too strong. Obviously much weaker if there is anyway of gaining the Reinforcement cards without buying them (e.g. a Remodel).
Midnight Gathering
Types: Action
Cost: $5
+1 Action. You may put your deck into your discard pile. Look through your discard pile. You may reveal an Action card from it; put it into your hand.
So it becomes an action card of your choice? I don't know, it seems too much like Band of Misfits, but limited by the number of other actions in your deck. Now that I think about it, that makes it probably way worse than Band of Misfits; a huge part of Band of Misfits is the flexibility (I can use this as a Sea Hag/Moneylender now, but later it becomes a valuable engine component). Here, you still need to have that number of the engine components and any opening-game cards are dead). I don't think being able to grab bigger actions makes up for that? How many big actions will you be getting with enough money to spam $5 cost cards left over?
Pasture
Types: Victory – Reaction
Cost: $4
Worth 2 VP.
When another player gains a Victory card, you may reveal and discard this along with any number of cards from your hand. If you do, +2 Cards per Pasture and +1 Card per other card discarded.
So, effectively a cellar/lab when your opponent gains a Victory card, and a dead card otherwise. Could be interesting, I suppose, but I wouldn't buy it early, and by the time I want it, I'll probably only see it once or twice? Although cellaring during the green stage would be nice. I'll have to think about this card some more.
Trailblazer
Types: Action
Cost: $4
Gain a card costing up to $4.
When you gain this, reveal the top 4 cards of your deck. Put any number of the revealed Victory cards and Curses into your hand. Put the other cards back in any order.
So, there are a lot of Workshop variants, and people tend to group them all together and say "another workshop variant", but I want to try to look at each of them separately, because they deserve to be considered individually on their merits.
As I said with Sultan, this can mess with the opening split similar to Nomad Camp or Inn. I don't mind it as much here, because a) everyone can buy it (it's a $4 not a $5, which is a big difference for an opener), and b) once you've done that, it's a Workshop, not an almost $5 in its own right. Still, an interesting effect.
Obviously, likes Silk Roads/Garden rushes a lot. Can also be a terminal Scout (gaining itself), if you ever want a terminal Scout. Maybe an end-game engine as a (very) poor man's Wandering Minstrel effect?
Bargain
Types: Action
Cost: $4
You may trash a card from your hand. Gain a card costing exactly $1 more than it, a card costing exactly $2 more than it, and a card costing exactly $3 more than it. Discard down to 2 cards in hand.
When you gain this, each player (including you) may trash a card from his hand.
Probably better than Expand, and at $4. This card seems far too strong. Open this, hit an estate next shuffle, gain a Silver, another Bargain (trashing a copper), and a $5. That's way too strong.
Clairvoyant
Types: Action
Cost: $3
+1 Action. Look at the top card of your deck. You may put it into your hand. Otherwise, +$1 and either discard it or put it back. Look through your discard pile and put a card from it or your hand at the bottom of your deck.
So, can be a cantrip (if you hit a decent card or a Copper) or a peddler (for cards you don't want anyway). Not sure how useful putting cards back on the bottom of your deck will turn out to be in practice, but it's a novel effect.
Fence
Types: Action
Cost: $5
While this is in play, when you buy a card, gain a card costing exactly $1 more than it.
EDIT: Changed from "when you gain a card" to "when you buy a card".
Without the edit, this was ludicrous. With the edit, it's a much weaker Haggler.
Shaman
Types: Action
Cost: $4
+1 Action. Name a card. Reveal cards from your deck until you reveal an Action card with that name. Put it into your hand and discard the rest.
When you gain this, each other player discards any number of cards from his hand then draws a card per card discarded.
Similar to Midnight Gathering above. Cheaper than it or Band of Misfits, but with an on-gain penalty. I like this somewhat better (just because of that difference) but I'll want to see some playtesting to see if it works
Tinker's Wagon
Types: Action
Cost: $4
Gain a card costing up to $4.
When you gain this, move a card costing between $3 and $6 from the top of one Supply pile to the top of another.
Another workshop variant. You cover up a card, then later use the Tinker's Wagon to uncover that pile and then normally buy the card. Alternatively, you can use the Tinker's Wagon to gain itself, covering a card that you don't want but your opponent might early, sort of like an embargo. So that's the synergy between the effects.
I'm not sure how I feel about the mechanic itself; can you cover an empty pile, thus making it unempty? What if you (using highway/bridge) move the last Province to another pile, thus ending the game early?
Thrift Shop
Types: Action
Cost: $6
+1 Action. +$2. If this is not the first time you played Thrift Shop this turn, you may gain a card from the Thrift Shop mat.
When you gain or play this, place a card costing up to $5 from the Supply onto the Thrift Shop mat.
Clarification: There is only one community Thrift Shop mat. Each player does not have his own.
So, you need to stack it to do something with it. Which is tough to do with a $6, even one that acts as a Silver. I have a similar rules concern (do cards on the mat count as not being in the suppy at the same time?
Grandee
Types: Action
Cost: $5
+1 Buy. Gain a card costing up to $4.
When you gain this, gain a Gold; each other player gains a Silver.
So a Grandee is sort of like a foreign governor, which I assume is the motivation behind the name (which I like). The rest of the card doesn't really seem to "click". It can't gain itself without Highway, bridge, etc. None of the effects really synergize together, and a $5 needs to be powerful.
Construct
Types: Action
Cost: $3
Trash a card from your hand. Gain two cards each costing exactly $1 more than it.
When you gain this during your Action phase, +1 Card and +1 Action.
I like the on-play. It's a weaker Remake, which is fine. The obvious synergy with the on-gain is to make it like Rats, but gaining another $3 along with the second Construct. You can even make it into a partially powered up City that trashes and gains two Constructs. I like this card.
Missionary
Types: Action
Cost: $4
Reveal cards from your deck until you reveal a Victory card. Gain an Action or Treasure card costing up to the Victory card's cost, putting it onto your deck. Discard the revealed cards.
When you buy this, reveal a card from your hand. If that card costs $6 or less, gain a copy of it.
This is swingy in most decks. Seems like it would be nice with Alt-VP. Maybe too nice; buy this, reveal Gardens in hand, gain a Gardens. So a slightly better workshop in that respect, but riskier in non-Rushes. On the other hand, if you can trash your Estates, gain a Duchy at some point, and this becomes a workshop that goes up to $5. I'm not sure if I like that swinginess.
Chapterhouse
Types: Action
Cost: $5
+1 Action. +$1. Draw until you have 6 cards in hand. Discard 2 cards.
When you buy this, each other player draws a card. When you gain this, each other player with at least 4 cards in hand discards a card.
So, a sifting copper with an on-buy sift or an on-gain urchin for your opponents. I guess that's thematic, although I'm not sure about the name. Obviously more powerful with the ability to gain $5 cards, at which point it becomes an on-gain discard attack (although a weak one). Which I don't like. I feel like there ought to be some reason behind an on-gain attack beyond just hey, let's make an on-gain attack. Noble Brigand is a Thief variant which is (a) a weak class of attacks in general (so it's not overpowering) and (b) has fun interactions with e.g. Fool's Gold. IGG isn't technically an attack, but the combination of running out 2 piles at once is a key component of the card. This card just possibly attacks.
Barn
Types: Action
Cost: $5
+1 Card. +1 Action. Discard a card. If you discarded a Victory or Curse card, gain a Treasure costing up to $4. Otherwise, +$1 and gain a Victory card costing up to $4. Put the gained card into your hand.
When you buy this, gain an Action card costing up to $4, putting it onto your deck.
EDIT: Changed "When you gain this" to "When you buy this".
So, a somewhat more complicated workshop variant. More precisely, it's a cantrip that turns another card into a non-terminal Workshop that can't gain actions. And you get a little money if you decide to discard an action or treasure. And the on-buy gives you an action that gets top-decked. But it can't gain itself w/o Highway/Bridge etc. Not that the on-buy would trigger anyway. Maybe a bit too complicated?
Huntsmen
Type: Action
Cost: $0*
+1 Action. +1 Buy.
When you gain this, +2 Buys. During your Buy phase, this costs $2 more for each card you've gained this turn.
Don't like this. I don't like the concept of getting extra buys by buying a card, I don't like the tracking it requires ("wait, what order did I buy my cards in; do I have $2 or $4 left? I can't look through my discard pile to check"), and I don't like the on-play either.
Painful Journey
Types: Action – Curse – Reaction
Cost: $4
Discard any number of Curses. +2 Cards for each Curse discarded.
Worth –1 VP. When you would buy a Victory card, you may trash this from your hand. If you do, gain a Victory card costin less than the bought card and gain 2 Curses.
Clarification: You cannot gain this card when another card instructs you to gain a Curse.
Why is this a curse type? If the idea is to let it take advantage of it's own abilities, just say "+2 Cards for each Curse or Painful Journey discarded." And the penalties seem too harsh; I can't think of a situation I would ever buy this.
Wagon Raider
Types: Action – Attack
Cost: $4
Each other player may put a card costing more than $2 from their hand into your discard pile. If he doesn't, he gains a Curse.
While this is in play, when you buy a Gold, you may gain a Province instead.
EDIT: Added "instead" to the end of the text.
So, a weaker Sea Hag (no one will pretty much ever give you a $3 or greater card voluntarily outside of something like Moneylender), that becomes a terminal silver that can only buy Provinces and doesn't stack (but does make it easier to buy more provinces). So it creates a slog, and then occasionally helps you spike to Provinces.
Nomadic Village
Types: Action – Reaction
Cost: $4
+1 Card. +2 Actions.
When you gain this, put it into your hand.
When an opponent gains an Action card, you may discard this. If you do, search your discard pile for an Action card and put it into your hand.
Village that goes straight to hand (I'd honestly prefer it being top-decked, because with no gainers "to hand" is essentially the same as being gained normally). If your opponent gains an action card, you can discard it to do a Midnight Gathering effect, which is another reason I'd like it to go on top of the deck (so your opponent is on notice that you have it in hand this turn). But maybe that would be too oppressive. I'm not really sold on this card idea.
Stranger
Types: Action
Cost: $5
+1 Card. +1 Action. +1 Buy. Each other player discards the top card of his deck. Copies of cards revealed this way cost $2 less this turn, but not less than $0.
This seems like it would scale badly to multiple players. It also doesn't really feel "Hinterlands" to me. I suspect in practice you will usually be hitting Coppers and Estates early on, so it takes a while before it's good, and then you have the Smugglers problem ("stop copying me!").
Courier (B)
Types: Action
Cost: $2
+1 Action. +1 Buy.
When you discard this from play, if you bought no more than one card this turn, you may put this on top of your deck.
I like the idea of a "Walled Market", but this implementation is too weak; I'd almost never want it on top of my deck. Maybe if the top half were like Market Square instead.
Sawmill
Types: Action
Cost: $3
+1 Action. +1 Buy.
When you gain this, set it aside onto your Sawmill mat. At the start of each of your turns, you may put any number of cards from your mat into your hand.
Very similar, but without clogging up the top of your deck. I think this is a much better implementation of this concept.
Pyramid
Types: Action
Cost: $4
+1 Action. +$1. +1 Card per Pyramid you have in play. Discard one card per Pyramid you have in play.
When you buy this, gain an extra copy of it.
So the pile runs out twice as fast. I don't like that, especially since it guarantees that there will be an uneven distribution of Pyramids (6-4), if you are in a situation where this card is good and you want to spam it. And it seems like whenever it's good, it will need to be at least semi-spammed; if you only play one per turn, you payed $4 for an Oasis.
Lucky Coin
Type: Treasure
Cost: $4
Worth $1.
When you gain this, each other player with at least 5 cards in hand reveals his hand and discards a card that you choose.
I don't like on-gain attacks, and this is only an on-gain attack ($4 for a Copper is just clogging up your deck).
Used Land Salesman
Types: Action
Cost: $5
+4 Cards.
While this is in play, when you buy a card, gain a Victory cards costing less than it.
This penalty is far too harsh early on, and then too good on the last turn.
Wayfarer (B)
Types: Action
Cost: $4
Reveal cards from your deck until you reveal one costing $1 or more. Put all the revealed cards into your hand.
When you discard this from play, gain a card costing up to $1 per Copper you have in play.
This seems like a cute Counting House variant. I suspect it will rarely draw more than a couple coppers per-play even early on, which means you will be gaining more coppers, which means you draw more coppers. Eventually you get a lot of coppers and then play them and discard them to double-Province. My only concern is that it makes Hunting Party-X seem like a flexible deck type. Literally everything that isn't a Copper, Curse, or Ruins (or have lots of Highways, etc. in play) hurts this deck; even multiple Wayfarers can block the draw and choke the deck.