The question jumped in my mind as I rewatched Joel Schumacher’s Batman and Robin (1997) where, at an early scene of the film, Batman grabs the ice-gun pointing it at Mr. Freeze but doesn't have time to shoot.
Also, in the Toys "R" Us Replica Edition (1997) of the original DC comic Batman #121 The Ice Crimes of Mr. Zero! (1959), where Mr. Zero (after known as Mr. Freeze) first appeared, it looks to me that at the end of the story, Mr. Zero was attempting to reach his ice-gun, not to defend himself against Batman and Robin, but to shoot himself with the weapon's ice gas in order to counteract the deadly effects of the steam bath in which he was enveloped.
Most of us are aware that, as a result of an accident in his laboratory while experimenting with a concentrated freezing solution, Mr. Zero's physiology was altered in such a way that he was obliged to live in conditions below zero degrees Celsius.
I'm asking because, in case that happened in the DC Universe, wouldn’t be interesting to know if Mr. Freeze can be overly frozen or can manage to resist that which changed forever his life?