'Crossover Pack 4' really does manage to feel like a different game. You want more than two players for this one so that the Hidden Roles and Villainous Machinations can inspire maximum paranoia. There is a rules tweak that allows two player games, but these games are not as thrilling. I'm not sure any other crossover or expansion changes the flavour of play quite so much, and it is impressive that this set can manage that. You can see the little brother of crisis rules here in the 'challenge' cards, as players work to try and quickly overcome difficulties, and the Hidden Roles are a bit like what you can find in Expansion 3 with the Suicide Squad agendas. Here, though, players turn on players much more nastily and brutally. It's sort of beautiful.
If you've overlooked this set, I'd say give it another glance. 'Watchmen' pushes the DC game well into 'Elseworlds' territory, and you might thrill at the dystopia you find there.
The snake god Glycon may not approve, but as Alan Moore would never say:
'Oi loik magic, me, and though magic could not stop moi intellectual property from being exploited by the massive intercontinental and many-tentacled Chthonian commercial entity that is Time Warner, this game is a bit of foon.'