Need your input about a build I'm curious about - please share your feedback!

This league I'm interested in using some the new skill gems that either reserve or utilize big chunks of the mana pool for offensive or defensive benefits (archmage, arcane cloak, etc) as well as storm bind.

Last league I went for a trickster storm burst build and had a blast doing it (channeling in place was meh, but other than that I genuinely enjoyed the build). [https://pastebin.com/2U9XahAk]

I wanted to try out a build potentially focusing around storm bind (or storm burst again) and considering the new skill gems I mentioned above I was curious about the heirophant ascendancy (which focuses on mana).

I've never done a templar build (or started out on that side of the skill tree) and I am genuinely not sure how I should progress the build to make it work - especially since MOAR MANA becomes a major focus of the build and that it something that I don't know how to balance vs. actual + %damage/cast speed nodes.

In my trickster build I was pushing ~90 crit chance with ~550 crit multi, and I genuinely felt the damage was absolutely insane compared to anything I've done in the past. (If I adjusted everything correctly - POB says I do just over 1mil shaper DPS)

But this time around I don't know if, were I to go for a heirophant, I would have to trade away a lot of that damage potential (from crit chance and multi) to increase my mana (and ES) -- what I can't figure out is whether or not, at the end of the day, that trade would end up being a net gain or loss on my DPS after all the calculations are done - this is in reference to transfiguration of mind.

What sort of uniques (if any) should I be looking for? For leveing? Early mapping? Late end game? Is there anything that's absolutely a must? Is the "healthy mind" jewel above the witch starting point important? Is shaper's touch a BIS or are there alternatives (or just a crafted rare)?

From the research I've done my knowledge is very incomplete and I genuinely appreciate your input and wisdom. Thank you! (Also if you can try and minimize usage of acronyms related to nodes, items, or skill gems I'd genuinely appreciate it!)