@rrra well, if you break the immunity per se, full effect of cold mastery -res takes place on the monster. This will be a very strong buff for cold sorc actually.
What i wonder: Isn't it that if a monster is immune the -%res(conviction) or -res from lower res is only 20% effective?
Will the -%resist on fire also be at only 20% effectiveness? If so, would be kinda low reduction wouldn't it? I guess it's flat then?
Lvl 9 conv(from perf aura maelevolent) has -70% res. 70*0.2 =14 (this will lower and break immunities < 114 total res right?)
So if you have 1 perf -light res wisp you have 15% already. or would it be 15*0,2 = 3 which would enhance to ability to break by a bit but still let conv/ lower res the strongest options?