Engineer (Action, Cost:5)
+3 Cards
You may put a card on top of your Deck. If you do, +1 Action and discard a card.
It's always as good as Smithy, but you can choose to make it terminal by top-decking one and discarding another. If you do that, you don't increase your handsize but you get really good non-terminal filtering. That's fairly interesting and looks appropriately priced at $5. I like it.
Sweeper (Action, Cost:3)
+1 Card
+1 Action
Choose a card in your hand. Discard it, or trash it.
There has been some discussion on this, saying that this should cost $4. I am going to go further and say that it probably doesn't work at any price as is, but if a price had to be given it would be $5.
Sweeper gives cantrip trashing. That is very powerful. Off the top of my head I can think of 3 official cantrip trashers -- Upgrade, Junk Dealer and Rats. Upgrade and JD are pretty similar -- $5 cantrip trashing with a mild benefit. Typically you use these cards to thin out starting junk, so Upgrade's benefit is typically nothing for Copper and $3 cards for trashing Estates, while JD is just a flat +$1 every time. Rats is a $4 cantrip trasher with a drawback -- you gain another Rats. The thing about Rats is that it is actually bad for you unless you can combo it with something else -- TfB like Apprentice or Bishop that appreciates having more $4 fodder, or something that can manage the Rat population like Jack of All Trades.
So how does Sweeper compare? It actually matches Upgrade and JD in function as a cantrip trasher with a mild benefit -- safety. You said that you want it to
not be playable all the time without consequences, but you did not succeed there. Sweeper is entirely safe to play because you can choose to discard instead of trash. For example, say I draw Sweeper, Gold, Gold, Wharf, Province. I don't want to trash anything in my hand. Now, if Sweeper were a Junk Dealer instead, I would opt not to play JD at all. But with Sweeper, I can freely play it. I draw Gold? No problem, I can just discard the Province in my hand.
That safety means that I would definitely put it above $4. I say that it might be unpriceable because I feel that it would be too strong for $4 yet too weak for $5.
Now, all that said, it might still be OK at $4. It would be very strong, but it might still work. Rats has a drawback, but in some cases it becomes a big benefit (and the $4 cost actually makes Rats better in those scenarios). But Sweeper is certainly, absolutely too powerful for $3.
Street Market (Action, Cost:4)
+2 Buys
+(1) Coin
Choose a card from a supply pile that costs up to (5). Cards from that supply cost (1) less, but not less than (0).
Single card cost reduction is a concept that has been brought up before. The main concern is that it can get extremely difficult to track. If you can accept that though, it may still work fine. I'm not sure about Street Market though. It costs the same as Bridge. It provides one extra Buy, but it only reduces the cost of a single card, and it has a price restriction too. Street Market would be unable to reduce the cost of Provinces (without Highway or Bridge). Although the extra Buy can be useful, especially with cost reduction, I imagine that Bridge is far better. You could probably remove the $5 target restriction, and maybe even bump it up to +3 Buys to emphasize that niche.
Iron-Processor (Action, Cost:2)
+2 Cards
Discard a card. If it's an... Action card, +1 Action... Treasure card, +(1) Coin... Victory card, +1 Card.
The action option is pretty bad, amounting to a cantrip with filtering but at the cost of an action card. The Treasure option is also not great, leaving IP with Moat-level draw if you discard a Copper, or worse if you have to discard a Silver. But the Victory card option -- that's just about as good as a Smithy. The chance of not finding a Victory card to discard means that it's probably OK at $2. Still, it's a rather boring concept.
Avalanche (Action, Cost:3)
+1 Card
Name a card. Reveal cards from the top of your Deck until you reveal a card that is not the named card. Put the revealed cards into your hand.
This is an alright idea, but it would be very weak in general. Even at $2, I would usually pass this up, because it requires both a good guess for the top card of your deck
and that the top of your deck have multiples of that same card for Avalanche to really pay off. While it can draw a bunch of Copper in the early game, that is extraordinarily luck-dependent.
I would suggest replacing +1 Card with +1 Action and dropping the price to $2. Making it non-terminal means it's a bit less harmful when you guess incorrectly, as it would then just be a cantrip.
You describe a "big play" scenario with Trader after you've drawn your whole deck... but man, that is such an unlikely scenario. Trader is not usually found in an engine that can draw the whole deck.
For those rare situations when you can do something really cool with this card, it doesn't matter if it costs a bit less.
Diplomat-Smithy (Action, Cost:4)
+3 Cards
The player to your left may draw a card. If he does, you do as well.
Others have noted that this is strictly inferior to Smithy in 2 player games. It may not be obvious at first though. The first thing to note is that this is never actually better than Smithy, because the player to your left can just decline the extra card draw every single time. The second thing to note is that the extra effect is NOT your choice. When the other player lets you draw, it's because
he really wants that extra card, or because he knows it doesn't help your or would actually hurt you (triggering an unwanted reshuffle, for example). The fact that it isn't your choice makes it inferior to Smithy -- you are giving an opponent a beneficial option, so it can only ever help him.
A bigger issue with the card, IMO, is that it gets political with more than 2 players. In a 3p game, playing the Diplomat-Smithy is like choosing to help out the player to your left. If the player to your right plays the card, you have extra incentive to do the extra card draw especially if he is behind the third player. I like that Dominion was designed to mitigate politics, so I don't really like fan cards that bring politics back in.
- For the following card, i have 2 versions of it:
Version 1:
Invention (Action, Cost: 6)
Gain an Action or Treasure Card costing less than this card. Put it in your hand.
Version 2:
Mach-Generator (Victory-Reaction, Cost: 6)
- Worth (2) VPs
When you gain an Action or Treasure Card costing less than this card, you may discard this from your hand. If you do, gain a copy of that card. If the gained card was not put in your discard pile, you may do likewise with its copy.
But i have also thought of another third version, which makes it a lot different:
Duplicate-Jester (Action-Reaction, Cost: 3)
Reveal a card from your hand that costs up to (4). Gain a copy of that card.
When any player gains a card costing up to (4), you may discard this from your hand. If you do, choose any player to gain a copy of that card.
Invention is pretty close to Altar. Invention cannot gain Victory cards, but it gains the card to hand. Altar trashes a card (which can be good or bad) and it is fixed at a $5 cap which means that it can combo with cost reduction while Invention can't. In the end, gaining the card to hand does make a fair amount of difference. It could be interesting.
Mach-Generator acts a lot like Talisman, but with greater flexibility -- it can duplicate cards up to $5 in cost, and it can react to gains rather than just buys. It's also worth 2VP. OTOH, Talisman gives +$1 and stacks with +Buy. The last part of the card is largely superfluous. Royal Seal and Watchtower can both be used on the copy anyway. A second copy of Nomad Camp will top-deck itself just like the first copy. What else is there? Explorer, I guess? That one interaction is not enough to warrant an entire extra sentence on this card.
Overall though, I don't find Mach-Generator to be all that exciting.
I don't like Duplicate-Jester at all. The main action is just a much weaker version of Workshop, which is already a really weak card. The reaction is political. Play a Witch, discard Duplicate-Jester to give one unlucky fellow an extra curse. I'd rather not have that.
Hope these comments help you refine your cards!
