I really like Embargo, and how it works best in non-mirror games, but unfortunately it's so weak because nobody wants to waste time buying it. So... it's another problem solved by heirlooms. I don't have any plans to perfect these cards, but those of you who like making fan cards, maybe there are some ideas for you.
Allowance - Treasure, Heirloom $0
$1
If you have at least 2 Actions in play, you may trash this. If you do, put a Prime token on a supply pile. For each Prime token on a pile, cards from that pile cost $1 more.
The Prime token idea comes from someone else, but I don't remember who. The only purpose of requiring 2 Actions in play is to delay the effect until around shuffle 3, by which point you can tell what strategies people are trying.
Shady Dealer - Treasure, Heirloom, $0
$1
You may reveal a Province from your hand to trash this. If you do, choose a kingdom card supply pile. That pile is no longer in the supply.
The idea of removing piles from the supply also came from someone else. But now it's permanent. This could be devastating. I am not good at coming up with names, but the idea is that when you get provinces, your kingdom becomes more respectable and you can banish your Shady Dealer, and their goods along with them.
Bounty - Treasure, Heirloom, $0
$1
At the beginning of your Night phase, put a coin token on a supply pile. (Whenever a player gains a card, they take all coin tokens from its pile.)
Bounty creates this little mini game of predicting which cards that you'll gain before your opponent.
I also came up with some cards to go with the Heirlooms, but these are just some basic throwaway ideas.
Town Guard - Action, $5
+1 Action
+$2
Draw up to 4 cards in hand.
Heirloom: Allowance
I don't really know what to pair with Allowance, but the idea is that draw-to-X cards tend to lead to divergent strategies, and also it defends against Militia which could be important if prime tokens are around.
Aristocrat - Action, $5
+$4
Reveal the top 3 cards of your deck. Discard one that the player on your left chooses. Put the rest on top of your deck in any order.
Heirloom: Shady Dealer
Obviously this isn't very good, but it helps you spike that Province, which is probably pretty good. Later Aristocrat will topdeck those provinces, or I guess discard them if your opponent is afraid of letting you trigger Shady Dealer.
Recruiter - Night, $2
Gain a card that you do not have in play costing up to $4.
Heirloom: Bounty
For a workshop variant, this isn't very good, but it helps you collect some bounty.
