All attacks which give +1 Action would definitely need to be in the set, meaning Spy, Minion, Urchin, Familiar, and Scrying Pool. I would suggest that Pillage and Marauder should also be in there, since a way to get some money is important. I would also say that on average, the cards should be relatively cheap, and also relatively mild, since otherwise everyone would be too bogged down to get anything. Here's my suggestion:
Spy
Minion
Urchin
Familiar
Scrying Pool
Pillage
Marauder
Swindler
Noble Brigand
Cultist
Cutpurse