Hope you enjoy my end-of-league build. I had a blast seeing it come to life.

Build "Basics":

Combine minion life, minion damage as well as levels (2 wep, amulet, minion helm) to get a level 32 Herald of Purity with 400k life on sentinels.

With Infernal Legion support as well as a Fortress Covenant for Minions take 160% increased damage (templar jewel socket), it takes 1.06 seconds for a sentinel to die.

Stack fire res lowering (flammability, ele weak, wave of conviction, combustion, EE) as well as inc damage taken (skitterbots, cinderswallow, infernal cry, others I didn't use but possible: aspect of spider, bottled faith) for big damage. Unfortunately the explosion is not a spell, so Unnerve doesn't work. We end up at 14.5M Minion Instability average damage per sentinel.

So how to summon sentinels?

You summon sentinels on kill, so combine 2 Writhing Jars with any DoT that will instantly kill the worms to summon 4 (max) sentinels on demand (has precedence over Infernal Legion Dot). I chose Death's Oath since in my testing, desecrate wasn't working properly and Death Aura is much more convenient than Plague Bearer, RF. This essentially forces us to run regen (level-boosted stone golem) as well as max chaos res since you are constantly taking 450 chaos dps.

With 19% reduced flask charges used on belt, I get 3 casts per Writhing Jar, and for bosses with phases, the Pantheon Ryslatha's Soul recharges charges to all life flasks (or hybrid).

How do you clear?

Ignite proliferation support (that's a gem???). With combustion + Raze and Pillage cluster notable (20% chance to ignite for minions), we get 74% chance to ignite. (PoB says 24% since it doesn't count combustion but seems bugged).

Since ignite proliferation kills count as the player, not the minion source, this will continue Herald of Purity's sentinel spawning, so if I run to packs fast enough, I don't have to use Writhing Jar beyond the first pack.

So for clearing I use HoP + Infernal Legion + Combustion + Ignite Prolif. For bossing, I switch to HoP + Infernal Legion + Conc Effect + Deathmark. (Helm links Minion Damage, Minion Life, Hypothermia)

Defences

Not the tankiest build around. HP pool is decent, every Writhing Jar press recovers 33% of life from Peak Vigour life cluster jewels and Herbalism anoint. With Pantheon upgrade, this nears 50% on low life. Fortify albiet inconsistent with Animate Guardian, possibility of Divine Flesh (since we max chaos res for Death's Oath anyway).

Since we do have tons of minion life and levels, we might as well use 8x taunting zombies with ~100k life each. Using +spell/+minion wands instead of +spell/+phys sceptres (which were easier to craft) can beef it up more.

Animate Guardian with ~200k life and 20k ES with Mask of the Stitched Demon has 93k regen per second. Note that the life isn't fully "accurate" since with Fortress Covenant minions take 2.6x damage, plus MI will kill any low life minions, but we do have res/meat shield (net .41 damage taken multi for elemental).

Important Details

• No quality for Infernal Legion as it would increase time for sentinels to die
• Global minion ele res is off limits (no Sacrifice or Indomitable Army which would be really good nodes)
• Storm brand EE so Wave of Conviction doesn't raise resists
• 6 passive medium cluster + 3 passive small cluster since it's hard to find as good quality nodes as those (minion life is biggest damage source on tree for this build)
• Additional Curse + Ele Weak gloves on AG allows for dual curse (use weapon range enchant since why not)
• Bleed Immunity using Bone Barrier
• There are tons of improvements to gear that I've realized after the fact from playing the build, but don't really want to recraft any.
• Profile: here character FlippyWormBomber
• PoB: https://pastebin.com/wuWrAr9K