[Andrew Hackard]

Restraining Order is a bit loosely written (as was true with many of the earlier cards . . . and some of the recent ones, too). However, it seems pretty clear that the intent is to prevent someone from playing cards specifically against the person who played Restraining Order, not preventing them from playing cards in general. I don't see anything preventing you from playing Illusion with a different monster (or even the same one) because that's not a card being played against the specific opponent who played Restraining Order.