edited some calcs...
Now lets look at how this affects a cursed target... This assumes the cursed damage increase is applied after all calculations
Cursed target 15% (Min/Max[Critical]) 158.125/221.375 [434.84375/608.78125] +20.625
Cursed target 30% +41.25
Cursed target 45% +61.875
Cursed target 60% +82.5
Cursed target 75% +103.125 maximum Critical = 926.40625
now lets look at heat death - assuming it works like arcane bolt/blast etc and is not affected by metamagics the formula would be 2000*2.2 = 4,400 damage (12,100 damage on a critical!) or 21,175 damage against a target with 75% curse.