+1

Very interesting.



Obvious comparison is to Archive. This, like Archive, is a not-a-terminal-action which adds one card to your hand for some turns.



Pro: it's easier to steer.

Pro: it can't be drawn dead.

Pro: has the potential to boost a larger number of hands.

Con: has the potential to boost a smaller number of hands.

Con: it doesn't add cards to your hand on the turn you play it.

Not sure if good, bad, indifferent or just different: it only sets aside treasures. (This increases your deck's Estate density if/while you have any.)



If you're playing BM, you have to hit $8 off of the other 4 cards in hand to get a Province, which takes a money density of $2/card. That sounds like a tall order. On the other hand, the closer you get, the more high-valued treasures you get to replay on your next 1-4 turns, which sounds like it almost guarantees a Province. BM with Crypt and a bit of terminal draw sounds like a really nice flavor of BM.



In engines, hmm... you can temporarily thin out your Copper while you trash down and build up, but the opportunity cost is another $5'er. Also, the Coppers will come back. Do you try to juggle the Coppers between two Crypts? If you have cards set aside with two Crypts, one of them has to run out before you can set cards aside again. Hm, maybe if your trashing is one card per turn, it's worthwhile to set aside a big chunk, then trash the incoming cards one by one.



When you're up to the point where your engine draws deck, do you really want to set aside multiple of your payload treasures? I don't think so. If I'm right, then if you have two Crypts setting aside one Gold each in an alternating pattern, you must draw one Crypt+Gold pair on each of your turns, rather than Gold+Gold if you had no Crypts, so that's a washexcept it goes wonky if you miss a turn. I see Salvager and Remodel as good Crypt partners: they trash Estates early and make good use of Crypts once they have outlived their usefulness.



Maybe Crypt really shines in Good Stuff decks? If you don't draw your entire deck, setting aside and replaying multiple high-value treasures is probably okayish-to-fine-to-great; it seems to get the most out of the upside with relatively little of the downside.