What is it?
The opposite of Incinerate. Rather than burn enemies to a crisp, you freeze them into solid ice. Hack and shatter the stationary sculptures before they thaw for a clean and efficient kill.
When should I use it?
While extremely useful against annoyingly acrobatic Splicers like the cart wheeling, back flipping ones in Fort Frolic, Winter Blast should never be used by itself. The ice you unleash will freeze your foe, but it will not harm him. Instead, a new life bar will pop up that shows your progress in breaking him to bits. Hammer away with traditional weapons for long enough and the ice - including the body within - will fall apart. Fail to finish the job and he will thaw, untouched.
At first, shattering a frozen enemy is easy; one gunshot or a few wrench swings will do the trick. But as BioShock progresses and the enemies get tougher, you will definitely need to upgrade your plasmid to Winter Blast 2 and Winter Blast 3 for continued success. That costs Adam and, potentially, Little Sisters' lives.
Winter Blast also has the same effect on security devices as Electro Bolt - it puts them out of commission until you can destroy or hack them. And while the cold you produce can put out fires, it can't freeze water. In Rapture's soaked environments, how cool would that be?
Does it work against a Big Daddy?
As a tool, but not as a weapon. Freezing Big Daddies is perfect for buying time - with the upgrades, Winter Blast could halt one for even longer than Electro Bolt. Shoot the icy sculpture with anything less than a few heat-seeking RPGs, however, and you probably won't complete the special progress bar before he thaws.
If you have enough proximity mines or trip wires, try setting a trap for the frozen Big Daddy. If you're quick, you can surround him with a nest of explosives, ready to detonate the moment he regains movement.