LOL! I actually just got the alert about this lol. I don't really have much advice but, just be patient. What helped me 3 star it was just trying to :
1. Let K.frost be the one to hit you with the super really early in the match. If you wait on shazam to super you then most likely that will be death...
2. Try not to do full combos on anything just do 3-5 hit combos and let the ice do the work for you in terms of getting the necessary damage. Watch where the iceblocks fall and coordinate, If you try to do long combos you will most likely get frozen/stunlocked.
3. Be patient it took me at like 6-8 hours on that one mission to get it.
May the force be with you. I may not be able to provide the most efficient method to do it but, you'll eventually get it.