OK. I tweaked things a bit. Mostly changed Villager, but I decided that Werewolf might be better with a coin bonus rather than a drawing bonus.
Villager
$1 Action-Reaction
+1 Card
+1 Action
You may play a Villager from your hand. If you don't, gain a Villager.
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When you would gain Curse, you may reveal this card from your hand. If you do, trash this card and gain a Werewolf from the Werewolf pile instead.
Werewolf
$0* Action-Attack
+ $2
Each other player discards down to three cards and gains a Curse.
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If you play a Silver while this card is in play, trash this card.
(This card is not in the Supply)
This Villager is a bit more Village-like. Essentially, if you have multiple Villagers they begin to function like a Village after the first. However, if they aren't busy being productive, then they get busy being reproductive, and you get more Villagers. From your perspective as King, the common Villagers reproduce like, well, Rats. This is nice, since aside from the reaction, Villagers are worthless self-gaining cantrips until their density grows large enough. The cost is $1 to imply thematically that they are lowly commoners, but also so that they don't become trash-for-benefit fodder in the way Rats are. Of course, Villagers become attractive in Gardens and Vineyard games, but that's fine in my opinion.
So this Villager doesn't give you a +buy, but still gives you a way to gain more of itself and build up density, which is nice since they aren't worth much individually and are spent when turned into Werewolves.
In some cases, you might even prefer to keep your Villager stack for the +actions rather than spend them on Werewolves.
The main reason for giving the Werewolves +$2 is to ensure that there is a virtual coin option to help the Silver-free deck get off the ground.
On the Silver mechanic. Thematically, the idea of Silver trashing Werewolf is fun. Many other Werewolf cards I've seen have tried to use Silver to trash an opponent's Werewolf. The problem with this is it encourages players to get more Silver, which has a tendency to push games towards big money, and also makes the decision to play a Werewolf needlessly risky and agonizing. By having your own Silver trash your own Werewolf, this reverses the incentive structure. It is now less risky to play your Werewolf, and the incentive pushes players away from Silver. This generally means away from big money, although it also adds value to alternative treasure strategies.
Rules Question: Mechanically, one reason that I went with "when you gain... gain instead" is so that gaining a Curse will only trigger a single Villager. I didn't want someone trashing a hand full of Villagers in reaction to a single Curse. Does the "when you gain..." language work the way I think it does? In particular, I believe that if I have two Traders in hand when my opponent plays a Witch, I don't get to gain two Silvers. That's correct, right?