Headmistress
Cost:5
Action
Choose 3 (Choices must be different): +1 card, +1 action, +1 buy, +$1, trash a card, gain a silver.
If you have 2 or more copies of Headmistress in play, discard a card.
This card attempts to fight its own analysis paralysis by punishing you for buying more than one. There are 20 combinations. Also, it should be "trash a card from your hand".
Academy
Cost:3
Action-Reaction
+$2
When you play an action card, you may discard Academy from your hand. If you do, +2 cards.
I think this is too strong. If you have any other non-terminal actions in your hand, it is a Lab for $3. If you have a terminal action in your hand, this tacks +1 card on that card. By itself or as the last action you play, it is a reliable terminal silver. The only weakening factor is that you cannot rely on this card by itself in an engine (I don't know if this beats BM).
Barricade
Cost:2
Action- Duration
+1 buy
+$1
At the start of you next turn: +1 card.
While this is in play, when an opponent plays an attack card, you may gain a card costing $2 or less. If you do, you are not affected by the attack.
I think this works, rules wise, but in any game with villages, this is too effective at punishing most attacks. Lighthouse only stops the attack, and Beggar doesn't stop the attack when it gains the Silver. This card seems fine for 2P, but is likely crazy in 4P, but it stops people from buying attacks at all.
Revolutionary
Cost:5
Action- Attack
Choose one: Each other player discards down to 3 cards in hand; or each other player gains a curse.
Each other player may trash a treasure card from their hand.
If this is the first time you've played a Revolutionary this turn, +$2.
I don't agree with GendoIkari. In many cursing games, coppers are too good to trash from hand. The curse option on this is probably a top-tier $5 by itself, so I think this would be better than Mountebank overall.
Tavern
Cost:4
Action
Choose one: +2 cards, put a patron token onto your tavern mat; or gain an action card costing up to $3 per patron token on your tavern mat, then remove all tokens from your tavern mat.
You +2 cards twice, then remove the tokens and gain a Goons? Seems like a trap card, but I don't see anything wrong here.
Books (support card)
Cost:0
Action
+1 action
Reveal the top 3 cards of your deck. Trash one, then put the rest into your hand.
(this is not in the supply)
Librarian
Cost:5
Action
Choose one: Gain a Books from the Books pile; or Reveal cards from you deck until you reveal a Books. Put it into your hand and discard the other revealed cards.
You may play a Books.
You must have an action card in play to buy this card.
When you gain this, trash an action you have in play.
This is difficult for me to predict. I assume that $4 might be good enough considering the action trash requirement.
Scholar
Cost:3
Action- Reaction
Look at the top 4 cards of your deck. Put one into your hand, then put the rest back in any order.
When another player gains an action card, you may discard this from your hand. If you do, gain a Books from the Books pile.
To get the perfect outcome from this, you likely need a village. The "another player gains an action" effect encourages people to play BM.
Private Funds
Cost:5
Treasure
When you play this it is worth $1 for every action card you have in play. If this is worth $5 or more, trash this card.
A card that could be worth $0 in an unlucky hand. As a Horn of Plenty variant, this seems to be okay. Does this effect count a King's Courted-action twice or three times? I never had to worry about that from a Conspirator.
Cafe
Cost:4
Action- Victory
You may play an action card from your hand.
+1 card
At the end of the game, you may trash a Cafe from your deck. If you do, this card is worth 5 VP.
I think the "you may play" bit is fine, though if the action is complicated, many players will forget to draw the card afterwords.
Poet
Cost:5
Action
+2 cards
+1 action
+$1
Put this card in your Poet mat.
You may buy cards on your Poet mat for $1 during your buy phase.
I don't know how often this would be worthwhile without +buy. Maybe in an Attack heavy Sea Hag game?
Philosopher
Cost:6
Action
Choose one: Trash up to 4 cards from your hand. Gain a card costing up to $2 more than the number of cards you trashed; or Trash Philosopher. If you do, gain a card costing up to $6.
Seems swingy, but no more than Forge already is.
Rebel Village
Cost:4
Action- Attack- Looter
+2 actions
Each other player with 5 or cards in hand trashes a copper from their hand or reveal a a hand without copper and gains a ruins.
When you gain this, gain 2 copper.
I don't like how much of a drag it would be to be on the receiving end of this is mass-multiplayer. The +actions as benefit weakens it early game, but it lets you play many ruins later...
Town Commons
Cost:3
Action
+2 actions
+1 buy
When you gain or trash this card, gain an action card costing up to $4 that is not a Town Commons.
Maybe "When you gain or trash this card, gain an action card costing up to $4 that you haven't gained this turn" since it wouldn't be able to instantly deplete a pile of a card with a similar effect that may get printed in Guilds. This is a good (if weak) effect that sometimes beefs up 4/3 openings into 4/4. I could see this and Necropolis encouraging double-terminal 4 openings.
