[3.1] [Build Guide] - Cast on Crit Low Life Max-Block Occultist

Xirgil's Crank lets us start energy shield recharge on one-fifth of blocks. The Occultist's Wicked Ward node gives us 4 seconds of uninterruptible recharge whenever that happens, meaning that against a large swarm of foes, we can expect to be continually recharging energy shield. This makes for a kind of survivability that other ES builds can struggle to obtain, barring significant investment in regen and Zealot's Oath. This with maximum block chance allows decent tankiness on limited health.

To get up to maximum block chance and spell block, we use Xirgil's Crank, the staff block nodes, a full set of Reckless Defence, and this beautiful item:

This both caps our block chance and massively reduces the downside of Reckless Defence. Obviously getting one with both these mods would be hard - there are a few on the market at the time of writing, though they're not cheap. However, getting one with just the block chance is quite adequate. A good second-best choice of secondary aura effect would be any of the Discipline effects - except for spell block, which would be useless.

To help crits land, we use Hinekora's Sight. It's a shame to lose the amulet slot, but there's not really any other way to get enough accuracy - maybe with an amulet, rings and helmet with godly rolls, this could instead be a rare.

Being low-life is a good way to get extra damage while being able to run all the auras and curses that we want to. Elemental Equilibrium adds more damage from our tri-elemental roster.

Ascendancy: Occultist, taking Wicked Ward, then Profane Bloom, and then Forbidden Power and Malediction in whichever order, depending on whether you want to go crit early or get a second curse going.
Bandits: Kill them all. Alira's crit multi and resists are a good choice too.

https://www.pathofexile.com/fullscreen-passive-skill-tree/3.1.1/AAAABAMBAQ18EQ8RLxFQE3EVfhZAGkgbJRvIHRQfGCL0KPoqCysKLKY0CjQxNbk2PTdmOw09Xz7xQXJCekZxSbFKLkuuTLNQMFBCUftSU1M1ValXyViuWfNca13yXqVgQ2ZUZp5oWGoBbAttGW1sbj1wUnIPcql6cHvXfPCDCYRIidOJ2IwLjDaMdo9GkNaRB5J9kyeUb5eVl7SX9JhvmK2bUZuhoS-nK6elrJisqrQMtzG5fLv8vJq-gL6Kw23JZ8rTzRbP3dAf1YvXltfP2VvbXtwj34rjhOXP6QLquuyw74jv6_GK9Cj3MvfX-Tf60vuL?accountName=Dirdle&characterName=Sayinei

Critical:





Non-critical:

There are alternatives for reaching or getting close to block cap without a Determination Watcher's Eye. Rumi's Concoction is one option; Gifts from Above is another if you can spare a ring slot. If you're not using the Eye, you can replace Determination with your favourite aura or heralds.


Energy from Within could be replaced with a good rare jewel or abyss jewel if you like, but you'll very probably lose ES for doing so.

Other

Priorities on the rest of the gear are simply ES and resists. The next highest priority is critical strike multiplier for damage. Lastly, intelligence can be nice for a bit of extra ES and accuracy for a slightly better hit rate. You'll probably also want to pick up some dex and str if possible, to allow leveling gems.
If you can get a good enough Stygian Vise and Jewel to put in it (or two jewels for Darkness Enthroned), that could be better than a Crystal Belt.

Socketed in Xirgil's Crank:
Cyclone - Cast on Critical Strike - Increased Critical Strikes - any three spells.
I use Ice Nova, Shock Nova and Firestorm because I like how they work together (shocking and freezing enemies while firestorm stacks up against tough single targets) and colouring the sockets for them wasn't too hard. But if you want to use actually good spells, that's an option too. If you can get level 21 gems for the spells, all the better. If you're not using multiple elements, you will want to spec out of EE.
Socketed in Shav's:
Enlighten - Discipline - Blasphemy - Poachers Mark - Elemental Weakness.
I use Elemental Weakness because I'm using all three elements. If you're only using one, the resistance-lowering curse of that element will be better, of course. Poacher's Mark gets us frenzy charges and makes sustaining mana very easy, as well as boosting hit chance substantially. Don't worry if you can't get enough dex to fully level PM - it's not necessary to do so. Enlighten must be level 3 or higher in order to have enough mana to use Cyclone.
Socketed elsewhere:
Cast when Damage Taken (lvl1) - Immortal Call (lvl3) - Increased Duration - Molten Shell (lvl10)
To create a RRRR item on an ES base, use the Vorici colouring technique shown here. If you hit RRRG before RRRR, use Vaal Haste here instead of Molten Shell.
Blood Magic - Determination
BM must be level 19 or higher.
Cast when Damage Taken (lvl 20) - Summon Lightning Golem
We don't have enough mana unreserved to summon a golem ourselves, so we'll put it on a CwDT set-up that will trigger only intermittently. You can vary the gem levels to try and get the best balance between golem survivability and frequency with which you re-summon it. Lightning Golem offers attack speed and is easier to colour for than Ice Golem.
Lightning Warp - Faster Casting - Less Duration - Swift Affliction/Arcane Surge
Arcane Surge is affected by Less Duration, but even so can be quite nice.

Ideally, we want the "Avenger's" prefix on as many flasks as possible. Reckless Defence makes us take a lot of crits, and this lets us regain some flask charges from that even if we're not killing anything. While we *are* killing things, we gain enough that other prefixes (Chemist's, Experimenters, etc) aren't needed. That said, don't worry too much about getting this perfect - it's more important to have a good range of suffixes.
For suffixes, we need Staunching and Heat, and badly want Iron Skin. Adrenaline, Grounding, Dousing and Warding are all good choices for the remainder.
In terms of flask choices: Diamond flask to maximise crits. Silver for attack speed. Granite for armour - without a granite flask up, we have *no* armour for Determination to scale, which is a bit embarassing. Basalt for extra physical redution. If you can balance your resistances, or if you only use spells of one element, The Wise Oak is going to be a fantastic choice. Otherwise, replacing it with a Sulphur or Quicksilver flask seems like the best choice - The Overflowing Chalice is excellent for flask-dependent builds like this.

We want the Brine King major pantheon, ideally with the upgrade from Puruna, the boss of the Atoll map, that grants the same benefit to freezes. While we're immune to stuns while cycloning, being stunlocked outside of it would be fatal. For the minor pantheon, Gruthkul offers good physical reduction and Shakiri helps reduce the problem of chaos degens, which are probably the biggest threat to this build. Switch to Aberrath for maps with burning ground.

I used Volatile Dead and Cremation to level. It was pretty horrible at times due to the lack of damage on the tree, but it's good enough to get to 81-85 and clear Eternal Labyrinth, at which point switching to this build becomes possible. It's up to you whether you go low-life as soon as possible or level as hybrid.

Bandits: Kill them all.
Ascendancy: Wicked Ward, then Profane Bloom, then Forbidden Power and Malediction

If you have a less painful way to level the build, please do share it.

All mods are doable except elemental reflect. The armour & block chance reduction mod should be avoided as well, but can be handled on lower-tier maps. No regen is doable but risky if you miss on Cyclone; better to avoid it if possible.

Don't.

The ideal belt for this build would be a Crystal Belt or Stygian Vise with the Increased Cooldown Speed mod which can appear on Shaper items. This would be unbelievably hard to get on a belt that also provides sufficient resistances and high ES, however.
Vaal Breach might make it far more possible to kill map bosses with this build. Or at least more entertaining.