Crit Firestorm Arcanist Brand build idea

Hi all, I've put together a PoB that I'm planning on league starting with (pending patch notes, of course). The build is a crit Arcanist Brand Firestorm Necro, with cast speed ramped by Corpse Pact and Eye of Innocence, to scale the first impact DPS. Why? Because I'm addicted to EoI and actually enjoy both Firestorm and Arcanist Brand (which are effectively totems that don't die).

https://pastebin.com/QtLxmt0m

I'm hoping to get some feedback to see if there are any obvious ways to make this stronger. Current build target DPS per brand is ~900K, without any corpse pact stacks. The goal is to keep the build very cheap. I'd even consider dropping the EoI gimmick and using a different class/ascendancy if it would yield substantially more toughness/DPS.

To level it, I'm going to run the typical spellslinging setup until I can save up enough chaos for an EoI, then make the switch. Everything else in the build is pretty easy to do as incremental upgrades (Martyr, clusters, anomalous gems, etc.).