I mean you can make it a villain for Yellowjacket, IDK about tossing something like that into the sandbox though. And making a machine that could freeze the city would mean the rest of the players would have to work that in if it actually freezes the city. That's more of a move for the GM's to make in the game... otherwise we run the risk of an even more convoluted scenario from Batman & Robin [the one with Arnold as Mr. Freeze].
~KL~
~KL~