I think there should be a card that can save cards from being trashed, granting any card a one-time Fortress effect.
It's a reaction card that, when one of your cards is trashed, gains it right back in some way. It can provide direct defense against trashing attacks such as Swindler, Knights, or Saboteur. It can power up trash-for-benefit cards and prevent losing valuable cards to high-power trashers like Death Cart and Forager. With the right balance, it can make some very interesting games.
Here are all the specifics that need working out:
Activation: Simply revealing the card and keeping it in your hand would probably make it way too strong for any cost, although Watchtower has the reverse of this effect and it stays in hand. Discarding it seems the most likely possibility, since that's how Market Square and Beggar are activated and they're pretty good cards. The other option is trashing it, which can balance out a really strong reaction or non-reaction but also turns it into a one-shot, generally frowned upon in Dominion-land.
Reaction: There are so many things that could happen to the trashed card. It could be a direct reference to Fortress, getting put into your hand, but that might make the reaction to trashing attacks overpowered. It could get discarded, which prevents playing it until next shuffle, although overdrawing in really thin decks makes that a non-issue. It could get topdecked, kind of a compromise between discarding and putting it in hand. Then there's the Possession trashing effect, where it could get set aside completely unplayable until cleanup phase.
Non-reaction: Because it can't just be a reaction. Should it be terminal or non-terminal? Stop card, cantrip, or draw? +Buy? +Coin? Trashing? Discarding? Should it be a victory card instead? A treasure card? I have a feeling that the stronger the reaction is, the weaker the non-reaction should be.
And finally, cost: The most expensive reaction cards are $4, so I'd want to keep this new card to a $5 maximum.
Oh and there's its name, but that's a different discussion.
So yeah, what would be the best way to make this idea work? What cool, risky, or overpowered combos can you find with all the different possible versions?
(This idea has probably been posed before, but I'm a lazybum and don't want to go through all the trouble of looking through threads until I find it.)