Vault doesn't let you Mine your Estates into Contraband.
Vault doesn't let you discard a Duchy to Coppersmith.
Vault doesn't let you Herbalist a Nobles back onto your deck.
Vault doesn't let you load up your Bank for big buys.
I see your point: the cards are similar. But Vault can do a lot of things Scavenger can't, and Scavenger... a lot of things Vault can't. There's enough difference that both can exist. My biggest question is whether I should keep it as is, or split "+2 Cards" into "+1 Card, +1 Action" since it is more of a combo piece than Vault. There's a good chance I should just do that rather than rely on Villages to move things along.
AJD pointed out the Estate->Contraband thing... but it actually introduces a weird rules situation. Is the Estate treated like an ACTUAL copper ($0 cost) or like a Copper that costs $2, or even a Copper that also has a Victory card typing? It's non-intuitive.
(PPE: I think this is generally answered now -- Rush meant Silver instead of Contraband.)
What happens if you played some Victory-Action cards before playing Scavenger? Does the Nobles you used for +2 actions also become a Copper? If so, does that mean it instantly gives you +$1? Do you still have the actions from it? I mean, it
should give you the $1 because it is now a Copper in play. But having a previously-played card
change after the fact is a really weird timing issue. If already-played cards don't change, then that means Herbalist can't topdeck the Nobles unless you play it as a Copper, which is probably not as good as playing Nobles as a Nobles.
It also adds confusion in other ways. When you play a HoP, will it count your Copper-Estate as just another Copper? I would assume so, but it makes it just a little bit more difficult to work out, especially for someone who is new to the game, or even new to just the card.
I think this still needs tweaking.