Usurer Part 2-$5
Action-Attack
Gain a silver, putting it into your hand
Everyone may discard 2 copper. If they do not: gain a copper, putting it in their hand. Each that did gain a debt token.
Usurer part two is not more disastrous for a deck than a kc-d mountebank, I think.
I considered having the Copper be gained to your opponent's hands, but then it's usually the same as if there was no debt and they gained the Copper to their discard because they'll just play the Copper to pay off the debt. Exceptions (e.g., if you play a handsize attack, if they trash or discard the Copper, if they're drawing their deck so they'd draw the Copper anyway, etc.) are too minor to be worth it.
The issue with handing out debt, is that if I KC a few attacks every turn, I could in principle hand out debt faster than the average payoff of my opponent's deck. Even worse if my opponent can do the same to me at the same time. It's better to hand out debt on buy. In principle, this could cause an opponent to take several turns to buy a card and pay off its debt. But it cannot pin a deck unless the deck has no payoff whatsoever.
Right, and I think the danger of allowing you to KC the attack unchecked is that if you pile on enough debt, it will take so long to pay off each single bought card that it may as well be a pin.
Good point about KC, although it would be hard to keep it up absent Watchtower or something due to the Silver-gaining. Maybe change it to:
Usurer(4)
Action - AttackGain a Silver.________________
When you discard this from play, if you have a Silver in play, each other player gains a Copper. Each player who gained a Copper in this way takes <1>.
That way, it can't be KC-ed. You could still play several copies a turn (although, again, you'd have to deal with the Silver), but IMO, that's no more of a threat than a Bureaucrat pin.
My only problem with an on-buy debt attack is that an Event that does this already exists (Tax). While there's room for both (cf. Embargo and Swamp Hag), I'd rather see something different first.