Got a lvl 84 blizz sorc - what's the best skill vs immunes? Nova? Charged Bolt? What?

static and gnasher

ew

telekinesis

Nova is bad in hell due to widespread lightning resistance, even when fully maxed. If it doesnt do enough damage to engage the monsters hit recovery, its garbage.

Charged bolt takes too large of investment to be usable, I'd say 40 points minimum and it does optimal damage at point blank range which can be inconveneitnt in many situations

Static field and level 1 thunderstorm is usable for single monster kills that dont have hp regen

I'd recommend looking into the fire tree, 3 usable skills are firewall, hydra, and meteor, all 3 are usable with a 20-25 skill point investment, I'd recommend trying each one to see which playstyle you like. Firewall has the highest damage return per skill point but some people dont like using it.

Fireball has been recommended as a secondary as well but I feel it is in the same category as charged bolt, although better than charged bolt, it still requires around 40 points to be effective in my opinion and playing fireball without a merc to tank, I dont like it personally.

none if not playing single player.

Firewall best dmg for low investment
Have fun killing extra fast seis with it though

Fireball less dmg, more accurate

This.

Also this. Using firewall is tricky. I buff with Hellplague sword and magefists so I don't have to drop any more than 10% resist at a time. You have to get the angles right with firewall but it does work well.

Meteor