Palanquin
Types: Action
Cost: $5
+1 Action. You may discard an Action card. If you do, +1 Card per $ it costs.
This seems dangerously broken, as mentioned by Robz888.
Quagmire
Types: Victory
Cost: $3
Worth 1 VP.
When you gain this, trash 3 cards from a Supply pile.
Very crazy, not in a good way. The first player to set up a triple-Workshop turn, or a double-Workshop with $3, or a $9 and 3 buy turn, just wins.
Trade Agreement
Types: Action
Cost: $5
+3 Cards.
While this is in play, when you gain a Trade Agreement, gain a card costing up to $5.
So these can just auto-pile? I don't like that...it means that if you have $5 and a Trade Agreement in play at the right time, the game ends one pile early. I mean I guess that's a pretty specific situation, but that might make it even weirder...do I empty the second pile, hoping my opponent doesn't have $5 and a Trade Agreement? I don't really like it, but maybe it's not broken.
Vendor
Types: Action
Cost: $1
+1 Action
When you buy this, +2 Buys.
This seems like a dead card on most boards. Trade off $1 for an extra buy and a dead card in your deck. I doubt that that is almost ever worthwhile. Obviously there are some cases where it is, but the odds that you get one of those cases while this is actually on the board seems really, really unlikely.
Factory
Types: Action – Reaction
+1 Action. You may discard a card that is not a Victory card. If you do, gain a copy of it.
When you gain a card, you may reveal this from your hand and put it onto your deck. If you do, put the gained card into your hand.
This needs a cost. This is actually pretty interesting, and I think I like it. I think I've seen the top half before, but the bottom half makes it feel a little more exciting.
Shoreline
Types: Victory
Cost: $6
Worth 4 VP.
When you gain this, +1 Buy.
This has problems with gaining not on your turn. It should probably say "When you gain this during your turn, +1 Buy."
Travelling Salesman
Types: Action – Reaction
Cost: $5
Discard any number of Treasure cards from your hand. +2 Cards per card discarded.
When another player gains a Victory card, you may discard this. If you do, gain a card costing less than it.
Is "it" the Travelling Salesman, or the victory card that another player gained? I would guess the latter. I think I like this. I thought it was strong at first glance but thinking about it a little more it seems reasonable.
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.
So the Reinforcement cards are in the supply and can be gained by other cards, just not bought. I think I've seen this card or something very similar to it somewhere before, and I like it a lot.
Midnight Gathering
Types: Action
Cost: $5
+1 Action. You my put your deck into your discard pile. Look through your discard pile and reveal an Action card from it; put it into your hand.
I think this is too strong, but I'm not sure. It makes it very easy to make sure your engine goes off whenever this is in hand. Actually this seems very similar to Band of Misfits. It's whatever you need it to be at the time. BoM can be any card costing $4 or less, while Midnight Gathering can be any card in your deck but not in your hand. But most of the cards in your deck are in your deck because you want them in your deck (at least most of the cards that you would want to draw from your deck), so it almost seems like this has to be better than BoM. I guess for BoM you don't have to take the time to buy the cards that you want, and you can't whiff by already having the card (but if you already have the card, then you most likely don't need a second copy of it right away), but it can whiff by having the supply pile empty. I don't know, I guess there are a lot of small differences between Midnight Gathering and BoM but I would guess Midnight Gathering is better about 80% of the time.
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.
This sounds bonkers strong. You trash Estates with it, gain a $3 and a $5, and a Bargain to trash a Copper from your hand. Then the discarding down to 2 doesn't matter, and you've replaced a Copper and Estate in your deck with a $3, a $5, and another Bargain. Granted, everyone else gets to trash too when you gain it. It is interesting though. I don't think that the discard down to 2 penalty really fits, maybe it would be good with some other penalty. I'm also not sold on the on-gain effect. It might be interesting if it gained Estates on-gain, like how Death Cart gains ruins on gain. It gives you stuff that you normally wouldn't like, and probably overall you don't like, but if you collide it with your Bargain, you can make good use of it. I'm not sure whether that would be a buff or nerf.
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.
This seems like a different way of doing what Midnight Gathering did, but cheaper and limited to action cards. But the restriction to action cards probably doesn't make almost any difference, since it's really an engine card anyway. Since I was worried that Midnight Gathering was too strong at $5, I really think this is too strong at $4. The on-gain is a nerf, but I don't think it's big enough.
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.
This is kind of interesting and could be a lot of fun. Really not sure on the balance, I could see it being really weak or really strong or just right...
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 really swingy in games without good Estate trashing and really strong in games with good Estate trashing. I would guess that it's actually pretty weak overall though, since by the time you want it, Gold-gaining is not spectacular. So actually it's probably fine. Not sure about the on-buy though.
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 gain this, gain an Action card costing up to $4, putting it onto your deck.
It's worth noting that these can auto-pile with just one Highway or Bridge in play, and even top-deck themselves while doing it.
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 think this is too weak. Normally I won't want it on top of my deck, even if I have the chance to. It's just a limited Pawn, or a Candlestick Maker without the coin token, that I can do several turns in a row. Might be important in draw-to-X engines that have no other +buy, but that's kind of specific. I don't know, not every card has to be a power card...
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.
Actually identical above-the-line text to the previous card. I would guess this is even weaker just because of the higher cost, where it competes with Silver. The below-the-line text is significantly better than Courier (B)'s below-the-line text, but I doubt it's worth it for $3 on most boards.