Three variants of Shyster, please comment if you have time:
SHYSTER 1 - 4$
ACTION - ATTACK
+1 VP
Trash a Silver or a Victory card.
If you do, each other opponent gains a Curse or a Copper (you choose).
Some justification:
There's a Victory card coming later, that specifically activates when it is trashed, not to mention of course, trashing Estates is useful. I took away the +1$ but rewarded you with +1VP, which I thought it a little more unique, as the Curse attack essentially becomes +2VP swing (while also clogging your opponent). Of course, activating the Curse is harder and narrower, so a lot of times you are just stuck with the +1VP (which isn't the worst thing in the world, but pricey at 4$).
Again, I don't think it holds a candle to Sea Hag, which is a simpler, straighter Curse attack. But it does have some additional utility. It can trim Estates early in the game, it can also be non-terminal if you choose to give up the Silver. If you can spam it, you can just accrue VP without activating the curse mechanism.
-----------------------------------------
SHYSTER 2 - 4$
ACTION - ATTACK
You may discard a Silver, if you do, all other players gain a Curse.
You may discard a Silver, if you do, +1 Action
Some justification:
This is a Hamlet-type card, that works off Silver. The first discard spreads Curses and the second discard keeps your turn going. It has danger of creating a nasty chain if your deck is narrow enough and full of Silver. But this is what makes it compelling.
--------------------------------------
SHYSTER 3 - 4$
ACTION - ATTACK
Choose one:
You may trash a Victory card, if you do, all other players gain a Curse.
or
You may trash a Treasure card, if you do, all other players gain a Copper
-----------
When you gain this card, gain a Curse.
Some justification:
I think without the self-curse mechanism the card is far too strong, but with it, I think 4$ is about right. Although IGG (which the gain mechanism copies) is priced at 5$ and Donald said this is how it wound being valued after testing, so maybe this should be worth 5$ too?
For some reason, designing a well-balanced Curse attack at 4$ is really hard for me.