Level 97 LL Blight Occultist^3.18

Notes

https://docs.google.com/document/d/1lfALtLVd32ov4ZfjEJh-_24F3g0ZQ_11oBgiZ4MQGi4/edit

Updates
May 10, 2022 - added a link to the early walkthrough (WiP) in the Leveling section.


Outline
-Profane Bloom explosions.
-Fits the requirements of a starter: a general-purpose, low cost, easy to put together, viable of unlocking all aspects of the Atlas.
-Offers the point-and-click playstyle of Bane as the clear/debuff skill mixed with the personal approach of Blight as the single target skill.
-Defences built around Wicked Ward, Ghost Dance, 100% chance to Suppress Spell Damage, and Purity of Elements with its Watcher's Eye modifiers.

Videos and PoB
Check brittleknee's overview of the gameplay here. The videos below are meant to represent the build as soon as it reaches the thresholds necessary for the corresponding boss fights. If you're not familiar with Path of Building, check this link.
-Uber Elder, https://pobb.in/3UFAS_C0pCMq (2.0M Blight DPS, 4.7 Cast Rate, 6300 ES).
-The Maven, https://pobb.in/3UFAS_C0pCMq (2.0M Blight DPS, 4.7 Cast Rate, 6300 ES).
-The Feared, https://pobb.in/HgSNNuEIEI_b (2.7M Blight DPS, no Hex Curses [see Vulnerabilities], 5.4 Cast Rate, 6700 ES).

The default setup, suggested upgrades and the leveling tree for Level 75 are available under this link: https://pobb.in/RYdlVZk9kwM3.
-The default version corresponds to a build capable of fighting Uber Elder and the Maven.
-The upgraded version corresponds to a build capable of fighting the Feared after small adjustments (change the amulet's Anointment for DPS, use Level 21 Blight, link Bane with regular Support Gems only).

Low Life and its interactions
We utilize Pain Attunement and maintain the Low Life status by using Clarity and Vitality supported by Arrogance. This way, with Level 20 Skill Gems, we reserve 1028 Life instead of any Mana. Level 1 Arrogance can be used to increase it to 1125 at the cost of the auras' effect. In any case, we're left with up to that much Life to use. This can be obtained at Levels 90+ with relatively small magnitudes of modifiers to Life.
Energy Shield becomes our main hit points pool but there's a concern that Chaos Damage normally bypasses it. Low Life builds often rely on Shavronne's Wrappings because of that. This isn't strictly necessary in our case and we can use rare body armours with higher Energy Shield values and other modifiers. Passive Skills like Withering Presence and One with Evil, together with '+1% to all maximum Resistances' crafted with Eldritch Embers, allow us to obtain a high amount of Chaos Resistance. Then, thanks to Evasion and Energy Shield Mastery granting '30% of Chaos Damage does not bypass Energy Shield', our 1028 Life limit with 77% Chaos Resistance is equivalent to 6385 Life with 0% Chaos Resistance. Meanwhile, any associated Physical or Elemental Damage will be mitigated by Energy Shield. We can also use Soul of Shakari for an additional '5% reduced Chaos Damage taken' and to limit the danger of Damage with Poison.
The high Chaos Resistance enables Chaos Mastery granting '+1% to Chaos Damage over Time Multiplier per 4% Chaos Resistance'.
Clarity fits well the build's need for Mana Regeneration. We don't need a significant investment into Clarity's effect and/or Mana Regeneration Rate to be never running out of Mana while channeling Blight but having some is useful.
Vitality allows us to use Chaos Mastery granting '+1 to Level of all Chaos Skill Gems' at the cost of 'Lose 10% of Life and Energy Shield when you use a Chaos Skill'. Note that the cost makes it possible for the character to commit suicide but we regenerate 12%-15% of Life per second.
The low amount of the maximum Life makes the character more vulnerable to Stuns. This is mitigated by using Soul of the Brine King, Practical Application, Unwaveringly Evil, and the inherit 50% chance to Ignore being Stunned while there's any remaining Energy Shield.

Defences
The Witch/Shadow area of the Passive Skill Tree offers many benefits and synergies for Energy Shield, Evasion, and chance to Suppress Spell Damage. In particular, we can utilize a few means to regain lost Energy Shield more easily.
Once our Energy Shield Recharge starts, it can't be interrupted by damage for the next 4 seconds thanks to Wicked Ward.
Ghost Dance improves our recovery through a synergy with Evasion Rating, which is provided here by Atziri's Step, Grace and flasks. The consequential chance to Evade is enhanced by Blind thanks to Curse Mastery.
Soul Thief provides us with important 'Recover 2% of Energy Shield on Kill'.
Instinct grants 'Recover 50 Energy Shield when you Suppress Spell Damage'.
In the default setup of the build we gain 53% chance to Suppress Spell Damage from the Passive Skill Tree. With up to 26% from Atziri's Step, we need at least 21% on other items. This is achievable with the Crafting Bench modifier on a body armour and the implicit modifier on gloves crafted with Eldritch Ichors. We can save a few Passive Skill Points with a Watcher's Eye granting the desirable Grace modifier and gloves that have an additional explicit modifier, which is assumed in the upgraded setup.
Our PoB configuration also includes an alternative approach where we settle for 92% chance, assuming even better modifiers on gloves, but relying on the combination of Void Barrier with the Labyrinth Enchantment for boots. This way we can use a Watcher's Eye with the Purity of Elements modifier granting Chaos Resistance and save the Passive Points used for One with Evil.
We mitigate Physical Damage in two ways:
by obtaining Endurance Charges through the Crafting Bench modifiers on our rings and Disciple of the Unyielding being anointed on our amulet,
by taking a portion of Physical Damage as Cold/Lightning/Fire Damage due to the Eldritch Ichor modifier on our helmet and on our Watcher's Eye. As Purity of Elements grants us Elemental Ailments Immunity, this won't make us get Frozen or Shocked.

Vulnerabilities
Atziri and rare monsters possessed by Tormented Blasphemers will reflect Hex Curses you inflict upon them. This is deadly and hard to mitigate, especially that their effect can be increased by 35% just between the Ascendancy Passive Skills and Quality of your Bane Skill Gem. You may want to avoid any content focused on Tormented Spirits and you shouldn't use Bane against Atziri while it's linked with Hexes. You can use regular Support Gems instead (e.g. Efficacy, Controlled Destruction, Void Manipulation). With the presence of Atziri, this is also an issue in the fight against the Feared.
The Maven can give bosses a temporary ability to apply a debuff dealing Chaos Damage over Time called Spatial Decay. While it won't directly kill you, it will stop your Energy Shield Recharge and it can't be removed in any way. Try to avoid getting hit after you hear a voice que (usually "Atrophy!" but she can use others), be ready to use Vaal Discipline, or disengage for its duration.
'Lose 10% of Life and Energy Shield when you use a Chaos Skill' is the downside of a powerful Chaos Mastery granting '+1 to Level of all Chaos Skill Gems'. Vitality and a few Passive Skills granting us 30-40 Life gained for each killed enemy are sufficient for the normal gameplay to overcome it, but there's a few factors and situations causing more problems.
In maps affected by lessen Life Recovery rate your character might commit suicide as your Life Regeneration doesn't keep up with the loss anymore.
Acceleration Shrines can make you so fast that your Mana Regeneration doesn't keep up with your Cast Rate of Blight. This can make your character start channeling again and again in a quick succession, losing Life each time and risking a suicide again.
The beams disabling your recovery during the Maven fight will also effectively take away your ability to deal damage.
(?) In the Archnemesis league monsters with the Entangler modifier would apply to you Thorned Vines. These would slow you down and make you take significant Chaos Damage based on both your total maximum Life and Energy Shield whenever you used a Travel skill (e.g. Flame Dash but also Withering Step). With a combination of the Life loss, this gets dangerous. If Entagler still works similarly in 3.18, then be cautious when you encounter it, especially in a combination with other modifiers. Don't spam your Chaos Skills and try to get rid of the vines just by running.

Spatial Decay

Thorned Vines


Leveling
Use Elemental Spells (e.g. Freezing Pulse and Holy Flame Totem) in Act 1 and Act 2, taking advantage of recipes for weapons with added Fire/Cold/Lightning Damage to Spells. Head to this document for a detailed walkthrough (WiP).
When you complete the quest Lost in Love in Act 3, you'll gain access to Bane. You can link it with Despair and switch to Bane/Blight setup. Link Bane with Temporal Chains when you allocate Whispers of Doom.
You shouldn't be using the Low Life setup until quite deep into the endgame. Start with prioritizing gear with Life as usually, using Energy Shield as bonus hit points.
Mind that Doedre Darktongue in Act 4 will consume curses you inflict upon her, gaining Unholy Might.
Suggested order of the Ascendancy Passive Skills: Void Beacon -> Withering Presence -> Profane Bloom -> Malediction.
You'll want Chromatic Orbs to be able to force red sockets on your wands by using the Crafting Bench, so remember that you can get some by vendoring items with 3 linked sockets each of a different color.
Beginning with Level 69 and before you obtain a body armour with 6 linked sockets, you can use a pair of Unique gloves, Allelopathy. They grant Level 22 Blight that will be supported by appropriate socketed Support Gems. Remember that this skill isn't affected by modifiers to Skill Gem Levels (as it's not granted by a Skill Gem), so you should prioritize other modifiers on your items while using it.
When you're around Level 90 and have a helmet and a body armour with high Energy Shield values, you can switch to the default Low Life setup. Adjust Skill Gem Levels of Arrogance, Clarity, and Vitality if necessary.

The default setup items
Wands can be crafted using Harvest Reforges (Chaos+) and Enchantments.
Helmets and body armours can be crafted using Dense Fossils. You can pick whichever Labyrinth Enchantment for your helmet you want as none is essential.
Gloves can be crafted using Essences of Delirium.
Amulets can be crafted using Harvest reforges (Chaos). Note that Citrine Amulets make it easier to meet our Attribute Requirements.
Iolite rings can be crafted using Essences of Envy (use Noxious Catalysts first).
Prismatic rings can be crafted using Prismatic Fossils.
Explicit modifiers colored with bright blue in PoB can be added with the Crafting Bench. Many of them can be unlocked by unveiling and some can be found in maps. Hover over them in the list of undiscovered crafts to check the details.
Implicit modifiers colored with green in PoB can be added by using Eldritch Ichors and Eldritch Embers.
Bated Breath is a common drop and it should be easy to obtain. 
Atziri's Step drop exclusively from Atziri.
In some gear/tree configurations the reliability of your Spell Suppression may depend on the boots' Labyrinth Enchantment but otherwise you can choose any of them.

Amulet Anointments
You can use Disciple of the Unyielding for Physical Damage Reduction and Elemental Resistances.
Tranquility, Corruption, and Exceptional Performance can provide more damage in different ways. Tranquility grants a moderately effective but general damage increase. Corruption usually grants the highest potential damage increase but it's tied to the number of Withered stacks applied. Exceptional Performance grants '25% increased Skill Duration', which helps if your ability to reach the limit of Blight stacks is restricted due to your Cast Speed, the mobility of bosses, or avoiding damage patterns. It's recommended to use it at least before you can craft increased Skill Duration of Chaos Skills on your wands.
Hex Master with its bonus to AoE is helpful if you want to focus more on the clear speed.

Map modifiers
'Players cannot Regenerate Life, Mana or Energy Shield' is the only modifier making maps completely unavailable to the build.
'Players have #% less Recovery Rate of Life and Energy Shield' and 'Players have #% reduced effect of Non-Curse Auras from Skills' make the gameplay more clunky and dangerous, you might want to avoid them as well.
'Area has patches of Burning Ground' is troublesome for Energy Shield Recharge but can be overcome with Soul of Abberath.

Tricks and tips
Withering Step quickly applies stacks of Withered to enemies and provides Elusive. It's limited by the fact that its effects end when you use another skill. However, using Blight refers only to the moment you start channeling. Therefore, you can cast Bane, start channeling Blight and cast Withering Step as the last to utilize it fully.
Corrupting a Blight Skill Gem can, between other effects, increase its Level or make it provide an additional Vaal version of the skill. Vaal Blight is very useful while mapping but to maximize your damage against end-game bosses you can use a Level 21 Skill Gem instead. You have a chance to obtain Level 21 Vaal Blight by using Lapidary Lens. However, you may still want to use separate Skill Gems, so that all Souls you obtain during boss fights will go to Vaal Discipline exclusively.
Void Sphere is helpful as a crowd-control skill (especially in Harvest encounters). Don't forget that it makes you vulnerable to 'Monsters reflect #% of Physical Damage' modifiers on maps. It's dangerous even with a low Level of the Skill Gem.
Massive Shrines will increase your Life, making you lose the Low Life status. This shouldn't be an issue outside boss encounters and increased AoE is actually helpful. Nevertheless, unless it's a Darkshrine, you can left click the buff icon to dismiss it.
Remember that the bosses of Cursed Crypt and Relic Chambers maps will cast a powerful nova when you curse them, consuming the curse.





Notes on HC
First of all, HC will require you to keep your gear up with the content you're approaching. We suggest the following rule of thumb: considering your Life, Energy Shield and effective reductions to Physical Damage taken, you should be able to take a 4500 Physical Damage hit in Tier 1 maps and an additional 450 for each further Tier, up to 11250.
For example, assuming 600 Life that can be used as a buffer, 8000 Energy Shield, 12% Physical Damage Reduction and 18% of Physical Damage taken as Cold Damage with 76% Cold Resistance, we can take a 8600/(0.18*0.24 + 0.82*0.88) = 11245 Physical Damage hit.
You should reduce some risks associated with the mechanics of the build: use '20% increased Effect of Withered' instead of '+1 to Level of all Chaos Skill Gems' from Chaos Mastery and replace Punishment with Enfeeble.
It's always possible to roll a map with enough deadly modifiers to kill your character. To make it harder for you to judge, some modifiers affect some monsters more than others. For example, modifiers from the group 'Monsters deal #% extra Physical Damage as Fire/Cold/Lightning' are very dangerous on monsters balanced around inherit Damage Conversion (like the Syndicate members) but moderately dangerous on monsters designed to deal Physical Damage only. The message is: respect your map modifiers.

Notes on co-op
I'll be starting the Sentinel league together with brittleknee, who will be playing a Poison Seismic Trap build and leveling it with Poisonous Concoction. You can check her video about it here. 

A part of the Occultist's identity is weakening the enemies, so she works well in parties, especially with other classes focused on Chaos Damage over Time damage.
Despair, Temporal Chains, and Punishment are each helpful in such a party on their own. Monsters will be additionally affected by Malediction and have 10% increased Damage Taken/Dealt.
Void Beacon provides -20% to Chaos Resistance of the nearby enemies and reduces their Life Regeneration rate.
Withering Presence provides automatic stacks of Withered over time, making monsters take increased Chaos Damage.
More characters in the party means that all auras can be used earlier. The other members can supply the missing Malevolence or allow you to replace one of your auras for it. You can benefit from somebody else's Determination or Summon Skitterbots as well.
Like in our case, the Saboteur can provide a common defensive layer through Born in the Shadows, saving you a Passive Skill point from a Curse Mastery and making monsters even easier to Blind. Its effectiveness depends on your Evasion Rating, provided for example by Grace.