In Sub-Zero’s Dead of Winter variation, he can Amplify Ice Ball, or DF1, to combo off of his overhead F2. Amplifying costs 1 bar of Offensive Meter, so it can be a waste if the F2 is blocked. To conserve your Offensive Meter, you must hit confirm the Amplified Ice Ball and only Amplify it if the F2 hits.
The reason this works is because Amplified Ice Ball requires 2 inputs: DF1 and AMP. This allows enough time to hit confirm the Amplified part so that Ice Ball will only be Amplified if the F2 hits. If the F2 is blocked, then the Ice Ball is punishable anyways so there is no reason to Amplify it.
This technique is very difficult and if not done correctly, you risk giving up a combo off of Sub-Zero’s F2. This should only be used if you can react quick enough and hit confirm 100% of the time.