[3.4] [PoB Pastebin] Glacial Cascade Avatar of Fire Totems - Chieftain - Optimisations?

Basic idea: Just a weird experiment I'm trying, basic concept is glacial cascade + 2 long winter jewels = 100% phys -> cold conversion. Then cold to fire support + avatar of fire = 100% cold -> fire conversion.

PoB Pastebin: https://pastebin.com/UJ79EBxs

Been pretty smooth through to level 82 so far. At the moment I'm using soul mantle for the extra totem and the level 20 spell totem support. I've only got it 4linked but since the socketed gems are supported by spell totem, it's effectively a 5link. I've been mucking about in PoB and it says that I'd be getting a lot more damage with controlled destruction or ele focus than added fire, so I know that's a simple but good optimisation to make, and I'm levelling a gem for it at the moment.

With 2 more links it would be similar to a 7link. Even with 5links it's pretty mana hungry, and I'm getting a lot of damage from hatred and herald of ash, so to get around mana issues I went Eldritch battery, which also enabled me to use arctic armour. I'm wanting to do a lot of mitigation since I'm in HC.

Not sure what the best optimisations I could do from here on out would be. If anyone has any ideas that'd be nice.