Level 96 MoM Crit Lightning Tendrils Guardian^3.23

Notes

About
Main idea of this build is to stack multiple Pendulum* effects. It is widely accepted that effects of this type are bad due to unreliability - so I decided to get as many as possible and make a build that can go crazy when all of them align. 
Those effects include:
 - Positive [Bound Fate] procs.
 - Fanaticism" buff from [Instruments of Zeal].
 - Divinity" buff from [Garb of the Ephemeral].
 - [Lightning Tendrils] - "Releases a Stronger Pulse every 3 Pulses, Stronger Pulses always Critically Strike".
 - [Curse Mastery] - "Your Curses have 20% increased Effect if 50% of Curse Duration expired".

Since [Instruments of Zeal] can be allocated through Forbidden Jewels I'm going Guardian as Ascendancy.

*"Pendulum effect" refers to effects that are active only some of the time or switch between different "modes" on a set timer. Name comes from the first effect of this type - Pendulum of Destruction. 

Dealing damage
To best take advantage of those powerful Pendulum effects I'm using [Lightning Tendrils] - it is a perfect skill for this setup for the following reasons:

 - LT guarantees a critical strike on every 3'rd pulse - I'm taking advantage of that and using [Controlled Destruction] and [Marylene's Fallacy] to boost that 3'rd pulse. This by itself is already a strong setup to scale LT damage. But since [Bound Fate] has a "Your Hits are always Critical Strikes" proc - I can occasionally deal full damage on every pulse rather than on 3'rd.
 - LT is a lightning skill, meaning that it benefits a lot from [Bound Fate]'s "Your Damage with Hits is Lucky" proc. (due to high variance in Lightning damage rolls)
 - It obviously benefits from "Divinity" buff (50% More Elemental Damage) and "Fanaticism" buff (75% more Cast Speed, 75% Reduced Cost, 75% increased Area of Effect)
 - I'm using Shield Charge to maintain "Fanaticism" - since LT is a channelled skill it's much easier to weave SC attacks while channelling. Channelled skills are not going to cause animation-locking. 
 - LT hits fast (and VERY fast when Fanaticism is active) - this allows me to maintain summons from [Unwavering Crusade] pretty much permanently.

I'm using [Anathema] and [Vixen's Entrapment] to apply Conductivity, Elemental Weakness, Enfeeble and Punishment. Curse Effectiveness scaling is very powerful right now.
Also, this is a [Bloodnotch] build - so I'm going to get stunned a lot. This allows me to use [Caster Mastery] - "25% more Spell Damage if you've been Stunned while Casting Recently".

Defences
This build is insanely tanky. Only DoT damage can cause some issues - which is standard for Petrified Blood build.

Block
Since [Instruments of Zeal] already causes me to both attack and cast spells, I can also maintain [Bastion of Hope]'s buffs 100% of the time. 
This combined with using a shield and [Tempest Shield] puts me at ~50% Block and Spell Block. 
From there capping both types of Block is possible. In fact, I can cap Spell Blocks just from the passive tree.

Recovery
 - I'm using the standard [Bloodnotch] + [Immutable Force] + [Petrified Blood] combo to get big recovery. This is further enhanced by getting [Trial of the Faith] notable and Life Recoup on a ring. 
 - For life leech I'm using Doryani's Lesson, and thanks to Petrified Blood I can overleech. 
 - ES leech is also important since I'm using [Eldritch Battery] + [Mind Over Matter]. Lucky [Vixen's Entrapment] provides that. 

Ailments
 - Elemental Ailments - this build is fully immune to shock (from [Tempest Shield]) and reduces duration of every other ele ailments by over 100% with [Solipsism] (this is equal to being immune unless you are standing on a ground effect). 
   Since I must use [Supreme Ostentation] to wear [Garb of The Ephemeral] I can pick [Solipsism] for free. And since I'm reducing Ailment Duration by over 100%, I can also get [Lethe Shade] for free. 
   I'm also running [Time of Need] - just in case.
 - Bleed - I'm running a Bleed Immunity Life Flask and a charm with "Unaffected by Bleeding While Leeching".
 - Corrupted Blood - "Corrupted Blood cannot be inflicted on you" from [Protection Mastery]
 - Poison - "Cannot be Poisoned" ring corruption.

Other
There are also 2 Pendulum effects that will occasionally boost defences even further: 
 - [Bound Fate]'s "Attacks cannot Hit you".
 - [Divinity]'s "20% less elemental damage taken".

[Radiant Crusade] is also worth mentioning - If you can pre-cast it before a big damage spike, it's a free 20% damage reduction. 
This can be the difference between dying or surviving Uber 1-shorts. 

Dealing with [Bound Fate]'s downsides
 - Hits against you are always Critical Strikes" - this can be countered by getting [Stun Mastery] "Hits against you Cannot be Critical Strikes if you've been Stunned Recently". Another option would be getting 100% reduced Extra Damage from Critical Strikes - this can be achieved through tree passives and a Shield mod. Note: [Garb of the Ephemeral]'s "Nearby Enemies cannot deal Critical Strikes" will not work.
 - Attacks against you always Hit" - I simply don't rely on Evasion for defences. I still run Grace however - it seems worth it.
 - Damage of Hits against you is Lucky" - this could be countered by using [Lori's Lantern]. This is a very good ring for this build anyway. 
   And since it's cheap, it's easy to get good corruption on it. 
   In the end I decided against using it however, since "Lucky Damage" downside does not seem to actually be that bad. It would probably be a bigger problem If I was not crit-immune.