ACT 1:
Item regex: "-\w-|Runn|rint|ll g|Incl"
Use 
Freezing Pulse as your main damage skill after Hillock. Links will be 
Arcane Surge Support + 
Added Cold Damage Support. Up until you get added cold, you can use 
Summon Phantasm Support, which helps slightly to keep enemies off you.
Buy or pick up a second wand or shield with % spell damage on it before the mudflats.
Kill enough mobs on the coast to level up your 
Freezing Pulse to level 2. It'll help immensely with the mud flats, and you can do so pretty easily while you're running through the coast. Just pause for a few seconds when you have a long trail of mobs behind you and blast em.
Look for these items, or buy them from Nessa:
Jade Amulet
Heavy Belt
Sapphire Ring
You can get a Sapphire Ring by vendoring a blue skill gem, such as the fireball skill you got in the beginning, with an iron ring.
Also buy 
Shield Charge + 
Faster Attacks Support. Use them if you find a spell damage shield base with 3 sockets, since it'll speed up your campaign journey quite a lot.
Basic skill rotation early is 
Frost Bomb > 
Holy Flame Totem > 
Flame Wall > Freezing Pulse
You get 
Ice Nova after the caverns of wrath waypoint. It's bad early, so level it in an offhand.
Gems to obtain:
Frost Bomb
Arcane Surge Support
Shield Charge
Faster Attacks Support
Ice Nova
Frostblink
Clarity
Holy Flame Totem
Flame Wall
ACT 2:
After the Chamber of Sins, I drop flame wall + holy flame totem. Your new combo will be 
Frost Bomb > 
Cold Snap > Freezing Pulse
Use the corruption altar on 
Cold Snap.
If you drop an early alch or two, i would pick up Vaal Cold Snap if you don't get it from the corruption altar, since it'll give you easy frenzy charges for the rest of the campaign and early maps.
I generally use Cold Snap as my main clearing skill here with the occasional Freezing Pulse spam for bosses. You can also use Ice Nova if you wish, but it's pretty bad early.
Links:
Freezing Pulse + 
Added Cold Damage Support + 
Arcane Surge Support + 
Faster Casting Support will be your 4th link if you get another 4 link.
Vaal Cold Snap + 
Cruelty Support + 
Controlled Destruction Support + 
Elemental Focus Support
Shield Charge + 
Faster Attacks Support
Frostblink
Clarity
Herald of Ice
Frostbite
Gems to obtain:
Herald of Ice
Cold Snap
Increased Critical Damage Support
Controlled Destruction Support
Power Charge On Critical Support
Faster Casting Support
Cruelty Support
Elemental Focus Support
Tempest Shield (ONLY IF YOU PLAN ON USING WAND/SHIELD)
Offhand or empty socket leveling:
Ice Nova
Faster Casting Support
Power Charge On Critical Support
Increased Critical Damage Support
Mana reservation for act 2:
Clarity
Herald of Ice
ACT 3:
Grab 
Zealotry and start leveling it. Don't turn it on until you have some mana reservation either from the mana mastery or the mana reservation nodes
Level 
Discipline, 
Automation, and 
Elemental Weakness in offhand or empty sockets
Gems to obtain:
Zealotry
Discipline
Frostbite (Start using this one)
Elemental Weakness
Automation
ACT 4:
Try to get Ice Nova of Frostbolts before Malachai. It's a good place to swap to this, but it's not required by any means. You can continue using Vaal Cold Snap and Freezing Pulse. Or swap Freezing Pulse out for the Ice Nova you've been leveling in your offhand.
IF using Ice Nova of Frostbolts, add in 
Frostbolt + Faster Casting Support + 
Volley Support + 
Returning Projectiles Support. You'll need to start using a chest armour at this point to fit all the skill gems in.
If you're low on sockets/links, you can drop Returning Projectiles Support and Faster Casting Support in Frostbolt. You can also drop any links in Vaal Cold Snap other than 
Bonechill Support.
Ideal Ice Nova of Frostbolts links are Arcane Surge Support + 
Spell Echo Support + Added Cold Damage Support. We'll swap added cold out for Power Charge On Critical Support after the 3rd lab.
Also set up 
Arcanist Brand here. Should be linked to Frostbite + Frost Bomb + Elemental Weakness (after getting 
Whispers of Doom notable on the passive tree)
Towards the end of the act, you'll get Bonechill Support. Link this to Vaal Cold Snap to increase the damage of your other cold skills when enemies are in the chilling zone.
Ice Nova of Frostbolts is only needed for single target damage! It will slow down your campaign immensely if you're using it for everything. Continue using Shield Charge + Herald of Ice explosions + Frostblink + Vaal Cold Snap for general mob clearing on the go.
Gems to obtain:
Bonechill Support
Spell Echo Support
Arcanist Brand
Returning Projectiles Support
PSA: Don't link support gems to Herald of Ice
You're pretty much set up for the rest of the campaign after this as far as gems and skills are concerned. When you swap to a staff, either in the campaign or in maps, you'll want a 4 link setup of:
Frostblink of Wintry Blast + 
Spell Echo Support + Faster Casting Support + level 1 Arcane Surge Support
Witch
Occultist
