All the listed cold damage that you see on your skills tab do not take CM into account. That 680-775 Frost Nova damage will be doubled when used against a 0% cold resistance monster and a slvl 17 CM.

That's exactly right. People often forget about Cold Mastery when comparing cold skills, but -100% cold resistance is *AT THE VERY WORST* worth as much as +100% cold damage, and in the best case scenario (monster with 99% cold resist), it could be worth up to as much as +10,000% cold damage (those are very rare situations, though, but it is possible).

A brief mathematical comparison of Nova and Frost Nova. For this excercise, I'm going to use some abbreviations to save myself some time.

40N = 20 points in Nova, 20 points in Lightning Mastery

40FN = 20 points in Frost Nova, 19 points in synergy, 1 point in Cold Mastery

60FN = 20 points in Frost Nova, 33 points in synergy, 7 points in Cold Mastery

80FN = 20 points in Frost Nova, 40 points in synergy, 20 points in Cold Mastery

Situation #1- against a 0% resistant monster, with no +skills.

40N = 603 average damage

40FN = 214 average damage

60FN = 398 average damage

80FN = 617 average damage

Situation #2- against a 0% resistant monster, with +10 skills

40N = 1292 average damage

40FN = 563 average damage

60FN = 981 average damage

80FN = 1142 average damage

Situation #3- against a 50% resistant monster, with no +skills

40N = 301 average damage

40FN = 125 average damage

60FN = 265 average damage

80FN = 509 average damage

Situation #4- against a 50% resistant monster, with +10 skills

40N = 646 average damage

40FN = 397 average damage

60FN = 736 average damage

80FN = 1142 average damage

Increasing the monsterâ€™s immunity only increases the amount by which Frost Nova will kick Novaâ€™s butt.

Yes, Frost Novaâ€™s going to cost a lot more skill points to develop (traditionally, I plan on investing about 70 points into FN and its synergies on FN Sorks), but you also get more for your buck. For those 30 extra skill points, you will kill just as quickly against non-resistant monsters, MUCH more quickly against resistant monsters, and youâ€™ll also get a huge chill length (10+ seconds in Hell), and a very powerful ranged attack to deal with monsters to scary to close to melee range with (Dolls, anyone?).

All said, a Frost Nova sork is every bit as viable as a Nova Sork.