Illusionist:
When another player buys a card you may discard the Illusionist and trash the gained card.
Thug:
When another player buys a card you may reveal the Thug and collect 1 VP.
both are obviously 5+ worth, maybe a potion added for Illusionist.
These have some rules issues...
With Illusionist, having the "attack" type wouldn't do anything other than cause confusion. The only thing that having the "attack" type does is to allow cards like
Moat to be revealed when the card is
played. If you can't play the card, you can't ever reveal Moat in response to the card. Note that
Ill-Gotten Gains doesn't have the "Attack" type.
Aside from that, it reacts to the player buying the card, which happens before they gain the card; so it wouldn't have been gained yet when you try to "trash the gained card". You could just change it to on-gain though. And I'm pretty sure that currently you can't ever trash another player's card; all trashing attacks force the other player to trash a card. This matters for things like
Market Square.
With Thug, it's not clear why you would want this to be an attack; it doesn't hurt or slow down your opponents. If the argument is that they will be more reluctant to buy a card in case you have it, then you
Fool's Gold should be an attack for the same reason.
But more importantly, with Thug, there's nothing stopping you from revealing it an unlimited number of times for unlimited
when an opponent buys 1 card.
Oh, and welcome to the forums!