I appreciate all the comments and alternative ideas. I would, though, like to hear any feedback on the most recent form of my idea, so I thought I would shamelessly re-post:
Attack-of-all-Trades (ha ha)
Action-Attack ($4)
"Each other player draws from his deck until he has six cards in hand, reveals two of his choice, then discards one of your choice and returns the other to his deck. Each other player trashes one card from his hand and gains a curse or a copper, your choice."
Great name. But this is just brutal, isn't it? Just the cursing attack alone is worth a $4 card, since having it go to Coppers when the Curses run out seems like a fair exchange for Sea Hag's top-decking ability. That leaves the rest of the card slamming players above and beyond what a $4 attack should do, even without any benefits to the player.
It's a really interesting idea to do all the different types of attacks on one card, though, and I'd love to see it work. (The first sentence, by the way, seems like a great attack component on its own card.)
I'm guessing, though, that it'll be hard to avoid the Dominion phenomenon where a card that does a lot of little things looks innocuous but is in reality an incredible game-changer. Jack of All Trades, Masquerade, Ambassador, and to a lesser extent Trading Post all illustrate the point. And we already know how brutal Followers is, even with a penalty for the player.
Thanks for the feedback. First of all let me say that I picked the price without too much thought, other than the fact that $4 is the minimum this card should cost. I don't think there is any way to judge the right price for this without playtesting.
I completely agree that this card is difficult to balance, for precisely the reason you mentioned: doing a little bit of everything can turn out to be huge in practice. But I also worried that all the various components of the attack could cancel themselves out. For an absurd example, imagine a card that combined Sea Hag and Saboteur*. Sounds brutal, right? But "Put a curse on top of your deck and then trash the top card of your deck" does nothing but take a curse from the supply and put it in the trash. [*I know that Sab skips curses].
As I mentioned earlier, a hybrid Militia/Ghost Ship might actually be less painful than either a Militia or a Ghost Ship. I think I've fixed that by letting the attacker choose which of the two gets discarded and which gets returned to the deck.
The reason for the copper element of the attack is that I was worried that the cursing and trashing attacks would cancel out. For reasons which Donald has made clear to everyone, trashing attacks have the potential to really mess up the game. This trashing attack doesn't skip worthless cards (weaker than Sab), but doesn't give you a cheaper card to replace what you lose (stronger than Sab). Part of the way I have designed the card to make sure the trashing attack wasn't overly strong (or swingy), was to allow the victim to choose which card out of six got trashed. But, having done that, I wondered how effective a cursing attack would be, since you may end up trashing the curses for them. Once the curses are gone, does the attack become a net-benefit to your opponent? That's why I decided to have the attack give curses or coppers: it still may get rid of junk for them, but it also keeps the junk coming.
There is a second purpose for dishing out coppers: it prevents abuse akin to KC/Masq. Playing this attack repeatedly will eventually run out not one but two piles (which is also the minimum for Saboteur).
And of course the card currently provides no benefit to the attacker. I figure that once the attack mechanism is suitably balanced, then the price and vanilla bonuses can be jointly decided on in order to keep the card balanced. For example, with no bonuses at all, this card is still stronger than Sea Hag (I'm pretty sure). So $4 at minimum and probably it should be higher. But how does this compare to Torturer? It both discards and curses, while Torturer let's the victim choose between those effects. It trashes, but again I'm not sure whether that's very brutal in combination with cursing. It gives no benefit while Torturer increases hand size by two, and - most significantly - the hand size reduction component of the attack doesn't stack, while Torturer (famously) does. So I think this would be underpowered at $5 with no bonuses.
What bonuses would make the card worthwhile at $5? Ghost Ship gets +2 cards, and I think this attack
might be stronger than Ghost Ship. Should it get +$2 coin like Militia? This is where I'd really appreciate some suggestions.