I just got into Torment. At level 67, I am soloing tier 29 nightmares (level 83 monsters) mostly without dying. So far so good. This is as a crackling energy/chain lightning sorc with no ice armor and no active frost nova. I have 3 points in frost nova to get vulnerable, but it only triggers from my lightning spear. Stuff mostly melts, and I have a ton of CC.
Active skills are teleport, flame armor, lightning spear, unstable currents, spark, chain lightning.
Enchants are frost nova, lightning spear
Gear is mostly mana reduction, lucky hit, crit chance with other stats in various damage types (conjuration, vulnerability, vs frozen, etc), with the exception that I’m using Iceheart Brais with a nifty max 20% roll on the re-freeze.
The strat is to start fights at range to build up a couple of crackling energies, then I teleport in and lay waste while dashing & teleporting around, casting lightning spear on cooldown, and popping unstable currents whenever needed. The crackling energy spawns keep my cooldowns pretty much constantly refreshed. My only deaths tend to be something like teleport lightning enchanted that hops on me right when I pop something and my old man reflexes don’t let me activate flame shield in time.