The +Buy from Counterfeit is not better because you can draw it with Venture.
Oh please. Let's assume we have a Venture deck - lots of Ventures digging through things to buy green. + Buy is assumed to be useful. What are the odds that a simple +buy (like say Festival) is going to be an option on a turn? The same as the odds of drawing my +buy in my starting hand. Say I have exactly 1 +buy. If I have 7 green, 6 Treasures, and one other card, then I will have exactly 33% odds of hitting my +buy when I need to go for something like Duchy/Estate. If I have Counterfeit as my +buy and just one gold, well there is about a 60% chance of drawing at least 2 Ventures; which means that we are around a 75% chance of having a +buy on "final" turns of the game.
Well what about a deck with Counterfeit as my only +buy, but also averaging a province a turn with high reliability? Well again if we assume 7/6/1 for other cards. Then It only has a 33% chance of hitting a +buy.
So Venture with any +buy other than Counterfeit/Contraband - 33% odds of being useful (and going down as deck size increases, like if you have cursing in play)
Counterfeit without Venture in play in a similar treasure based deck - 33%.
Odds with both - 75%.
Why it is like the odds of this outcome happening are higher than with either card alone or even some nonsensical summation of the two scenarios. It is almost like the sum of each effect is insufficient to explain the resulting outcome.
Now, is this a
big synergy, no it is not hence why I explicitly said that this was a
small synergy.
The trashing from Counterfeit is not better because you can draw it with Venture. The Copper trashing is good for Venture, but that's not special -- Venture benefits as much from other Copper trashing.
Bull.
Say I need to kill a final copper to get a reliable Venture deck. What are the odds of doing so with Moneylender? The odds that I draw Moneylender/C in one hand. What are the odds that I kill the Copper with a Counterfeit - the odds that I draw Counterfeit/C or that I draw Venture/C. Obviously the latter is more likely (having some non-zero increase in likelihood over Moneylender).
Does this sort of thing matter? At least at the margins. Take a similar case - Tunnel enablers. Sure Cellar can flip Tunnel, but it only has 4 chances to find the Tunnel. Warehouse gets 7. Similarly when you have a copper, you have 4 slots to hit a Moneylender to pair up. When you have a copper, you have 4 slots for a Counterfeit
and some quite high chance of lining up C/Venture -> Draw Counterfeit -> Trash C.
The odds that an ability will be used is part of what defines synergy.
Your second point is just about terminal draw, which is not an interaction between Venture and Counterfeit. Treasures can be better with terminal draw because they can't be drawn dead. That's it. You're saying that these two treasures have special synergy because they are both treasures? That's nonsense. Do Contraband and Cache have special synergy because they too can't be drawn dead with Smithy?
Please, read better. I'm saying that there is a synergy between A and B (Venture and dead draw), between B and C (dead draw and Counterfeit), and between A and C (Venture and Counterfeit). Call each of these values x, y, and z. I assert that the total synergy is > x + y + z.
For the set of boards where Venture is dominant or close thereto, a large percentage will be enabled by some form of dead draw. Counterfeit, when it is also an option will hence synergize with just about all the non-copper trashing enablers of Venture.
Your third point isn't a synergy either. Even without Venture on the board, Countefeit still allows you to get extra VP by trashing your Gold and Silver or other treasures. This is just what Counterfeit does, it has nothing to do with Venture.
For Pete's sake this isn't hard. Counterfeit without Venture is only useful in such circumstances when you draw it in hand with the treasures. This could be 100% with deck drawing engines or megadrawing megaturns - and virtually none of those instances are when Venture is worth a damn. If Venture is good (as in better than a Silver with a slight bonus), then we are looking at situations where we won't be drawing deck.
Okay so what are the odds that on a "final" turn you will line up Counterfeit and a say a silver in a deck that reliably hits 8? Could be fiendishly low (e.g. a Masterpiece deck where you might have below 20% odds). With a venture deck it is again the
union of drawing a Silver with counterfeit directly and drawing the Counterfeit with a Venture. Venture decks, ceteris parabis, ALWAYS have higher odds of drawing the Counterfeit than a comparably reliable treasure deck.
Duchess
allows you to activate Tunnel, yet somewhere we have to look at how often that "allowance" is made.
Do Venture and Counterfeit have some synergy? Sure, because Counterfeit can trash Copper, Venture can draw Counterfeit, and Counterfeit can be played on Venture. But none of these qualities are special.
I'm sorry, what makes something magically "special"? Do Tunnel and Warehouse have "special" Synergy - because you know there a bajillion cards that can discard Tunnel - like Duchess. I guess we should ignore that as not being "special".
Do me a favor and give me a rigorous definition of "special". As is you are just playing around with a giant no-true-Scotsman
Venture can draw other treasures for other bonuses; you don't need Counterfeit for that. Counterfeit is not the only viable Copper trasher for Venture. And Venture is not a uniquely good target for Counterfeit. Not to mention, all of these things had already been mentioned in the thread.
However, Counterfeit is a uniquely good target for Venture. Exactly one other treasure can trash copper; it has a search space of 1 treasure excluding treasures in hand. Exactly oen other treasure offers +buy, but it is uniquely bad for Venture as forced play can utterly trash your end game. You could argue that HoP functions the same as +gain, but HoP really doesn't like the uniformity of most Venture decks (though it likes Venture as a cheap unique in other forms of decks).
What is is a uniquely good target for Venture? Not generally Talisman, Cache, Harem, Igg, Fg, Pstone, Spoils, or Contraband. Royal seal competes on price and doesn't do anything special when you buy a Venture or green. Hoard & Bank are maybes, but that puts Counterfeit in a fairly, what's the word, "unique" position.
I know how to really kick this combo up a notch... remove Venture.
And this is the big problem, though I would take Counterfeit over most other copper trashers to build a Venture deck, I would not take Venture as my payload when viable copper trashing is out. Counterfeit is normally at least decent at building engines and it needs to be a limited board or have some
other Venture enabler to make me go Venture. Barring some other enabler (of which there are many that also support Counterfeit), then I don't see Counterfeit being enough to drive you to Venture.
If Venture is good enough for other reasons, I can see it driving you to Counterfeit.