Looking for suggestions with Cold BV leaguestarter

Looking for suggestions on an Occultist Cold-BV league starter. Budget: low (Mostly spending for 2 strong prefixes on staff)

If you've got suggestions on where to take it for min-maxing, that would also be great; I'm coming back after a couple of leagues so I'm *rusty* - should I go powercharges with 2x Void Battery? Something else? etc - I expect I'll want to respec eventually once I can craft/purchase decent cluster jewels, but don't want to assume I'll be getting them pre-red maps.

If anyone has a better-looking PoB using Elementalist instead of Occultist, I'm all ears, I'd just prefer to play a witch this league.

Tree has OK life (164%), 41/36 block (Would like to get this higher, but will probably require items/glancing blows), and has some regen on block and the Divine Shield keystone. I'm only seeing ~5k armor though which seems very low. Occultist ascendancy will give me 20% reduced damage taken from hits, and then enfeeble on top (Perhaps that should be temporal chains instead). Playing a build that freezes & chills and is mobile is also itself a defensive layer, so hopefully this character won't die too often; Damage is 500k at 10 blades pre-buff, should reach ~750k+ post-patch? That seems pretty good for a league starter that's not minions, but my internal metrics might be out of date.

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https://pastebin.com/Dn2xGgew

UPDATE: ok, so at what point does cold BV start to feel good at bossing, damage wise? The switch to power charges seems to just provide more damage, and somewhere along the way of upgrading it, it starts to feel fine. The consensus is clearly that I shouldn't start with BV, but I'd like to know what the magic number is when I can switch to it.