There was quite a bit of discussion as Goko appeared about the idea that some cards might be created that were "online only;" cards that would be interesting, but either impossible or prohibitively difficult to track at the gaming table, but easy to do on the computer. I thought I'd try to create a few.
Tower
Action - $2*
+1 Card
+1 Action
You may trash this card. If you do, gain a cheaper card
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Each time you play this card, the cost of this card increases by 1.
This is just an expensive cantrip when purchased. However, each time you play the card, its cost increases. After 5 plays, you can trash it for a Gold; after 7 plays, you can trash it for a Province! But this requires tracking each individual card, and different copies of Tower in your deck may have different costs at the same time. Not to mention that, when trashed, it retains its cost, meaning it has to be tracked for Rogue and Graverobber.
Pocketwatch
Treasure - $5
Worth $1 for each copy of Pocketwatch in your deck
The first one is an expensive Copper; the third one is three cheap Golds, effectively. But keeping track of this requires either a mat or some sort of tally--either of which gets messed up when the card is trashed.
Chancellor
Action - $3
+$2
You may shuffle your deck and discard together. If you do, take half of the cards (rounded down) and place them in your discard pile.
An odd card, probably with a power level similar to the real Chancellor; it allows you to (possibly) recycle your used good cards, without automatically recycling your dead cards. Well, probably; I'm not actually saying this is a good card, just an example. Sitting at the table, you have to count the newly-shuffled deck, then cut that number in half and place those in the discard pile.
Astrolabe
Treasure - $5
Worth $1 per $12 of the total cost of the cards in your deck
Really, you don't want to have to deal with this at the table.
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Probably only the first two are even close to good ideas (I quite like the first one). But I thought it was an interesting thought experiment. Anyone else have good online-only cards?