Hi there!
I recognized that in Dominion there is an invisible currency: handsize.
The normal case is that you convert your handsize into $ by having Treasures or other cards providing +$.
Now, cards that let you "discard for benefit" do other things with your handsize. This means you discard a number of cards to get a reward - prior, after, or conditioned by the discarding.
Official examples of this concept are mostly Sifters (like Cellar or Embassy) and turning cards into $ (like Vault or Horse Traders). Man, I really like Hinterlands for having Sifting as core concept. Using a broader definition, we could include disappearing cards as well (like Workshop or Festival) - not sure whether those should belong here.
But all of these cards have in common to synergize well with Library (or Watchtower/ Jack), Tactician, and Minion.
Are there other things to turn handsize into? I highly appreciate your comments!
COURIER (Action – Reaction) P
+1 Card
+1 Action
Discard any number of cards. Gain a card costing exactly $1 per card discarded.
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When you would gain a card other than during your Buy phase, you may discard this from your hand. If you do, gain a card costing up to $2 more instead.
This (at cost $4) was my suggestion for the Hinterlands Treasure Chest Design Contest card. Meanwhile, I came up with tons of variants of Courier. I think the easiest fix is the Potion cost so that you can't gain other Couriers. Maybe a non-Victory clause would make sense for the Action?BUTLER (Action) $3
Discard a card. Gain a card costing less than it.
Simplified version from the Queue pile thread where it got zero feedback. It is quite strong when you discard a Province, but Explorer rewards Provinces as well. Maybe it needs some vanilla addition or a cost tweak a la Border Village/ Peddler?CASTLE GATE (Action) $5
+1 Action
Discard any number of cards. Draw until you have 5 cards in your hand.
A mix of Grand Cellar and Dungeon. It wants to be a new enabler in the Library/ Minion family.