Well, this is about to be one of the most scuffed "build showcases" this sub has probably ever seen, but just in case there are any undecided exiles out there who really want to start with something so off-meta it can't even be found on poe.ninja, I didn't want to withhold my "research" from 3.19.

Having said that, this build was not min-maxed and it is by no means optimal. It's just different for the sake of being different. If you're looking for something overpowered, this is not it.

Final POB for the impatient:
https://pobb.in/DD8sCS36uMCP // https://pastebin.com/YwfZVAbG -- Final Snapshot of Character when I stopped playing the league

Please note: the configuration is set to 10 Wither stacks only and no Focus to give a more realistic, but potentially conservative DPS number.

Some stats with my gear:
DPS: ~5 mill as configured ~9 mill buffed (as of 3.19. likely more in 3.20 due to curse changes, but hard to calculate until PoB is fully updated)
Life: ~4.6k with Divine Flesh // ~5.2k without Divine Flesh
Armour: 32k in hideout // 50k with flasks and MS
Res: 86% chaos res with 75% ele taken converted = ~83% max all res
#Edit: the new version of PoB seems to massively inflate the DPS (probably because of curse changes). DPS might have gone up, but definitely not tripled. Also, the build will require an extra point and you need to reallocate whispers of Doom when converting to 3.20

Build summary
Using Volkuur's Guidance cold version gloves to allow Ice Spear to poison. Ice Spear is actually great for poison for multiple reasons (see below) and Profane Bloom carries map and pack clear pretty well. End-game version uses Incandescent Heart in combination with Divine Flesh to convert 75% of elemental damage taken to chaos with 86% max chaos res to mitigate ele damage and fairly significant Armour values + Endurance Charges for phys mitigation. EB is used to sustain very high mana cost and to enable Malevolence Blessing, as ES would be useless with Divine Flesh otherwise. During mapping I mostly run both GMP and Greater Volley to get a much better spread. Gem swap with Deadly Ailments for single target is possible, but not really necessary later on except for Guardians/Conquerers/Pinnacle Bosses

Why Ice Spear?

1. Ice Spear is one of the few skills in the game that has a "in-built" barrage, meaning any additional projectiles can hit the same target. As poison isn't affected by the downsides of GMP, it becomes a ~200% more damage multiplier (without further sources of additional projectiles), which nicely counters the gigantic downside of 50% less poison duration from Volkuur's

2. Adding further projectiles is possible and makes Life gained on spell hit a somewhat viable life sustain method on single target

3. Ice spear has 600% increased crit chance in the second form which means it is super easy to trigger Elemental Overload with 0 investment in crit. Yes, EO does increase poison damage for poisons stemming from ele dmg, in case you didn't know.

4. Once second stage is reached, Ice spear has very high projectile speed and infinite pierce

5. (Although not Ice spear specific) Using cold damage to poison means that we can actually make use of the 15% more dmg multi from Frigid wake on top of the defensive benefits

Pros

1. Very nice meme value. It's so off-meta I couldn't find anyone else online who has actually done this before. Also, frequent responses to people finding out my build were "dear god" and "WTF"

2. Many gear pieces are relatively cheap because it's so off-meta. I got the Corrupted Volkuur's for under 10c, my end-game weapon for around 50c because the specific combination of mods is not useful for any other build out there.

3. Many different defense layers: Temp chains, chill (occasionally freeze from Frigid Wake and AA), hinder, end charges, chaos conversion, Arctic Armour, decent Armour value + MS, enemy damage reduction from both Frigid Wake (10% hit) and Withering Presence (15% DoT), CWDT Ball Lightning + LGoH

4. Don't care about reflect (because GMP + Greater Volley/Deadly Ailments makes your hit damage tiny)

5. Absolutely league-start viable. No expensive items required to get started and make it to T16. I farmed all the currency invested into this build on this character

6. ~~Easy to get nice jewel corrupts for Energised Armour and Careful Planning~~ RIP

Cons

1. Poison ramp-up can be annoying

2. Absolutely terrible at Legions due to aforementioned Ramp-up and the fact that Profane Bloom Explosion are not big enough to chain

3. Have to stand still to deal damage

4. Mobility is not great. Could probably be improved if you get rid of Wither Totem and include Shield Charge because Wither should be covered by Withering Presence + Timeless Jewl node anyways

5. No Evasion, Block, or Spell Suppression --> prone to stuns esp. early on

6. Bad life sustain until you get a decent amount of LGoH via Watcher's eye (which is missing in my final PoB because I muled it to another char btw)

7. Not SSF or HC viable

8. Pain to cap poison chance early on and Profane Bloom not poison chance capped at all

9. not sure if Uber viable because I'm a fucking scrub and never got that far lol

-------------------- Further PoBs / Progress-----------------------
https://pastebin.com/yJEA98eS -- Original theorycraft before league start https://pastebin.com/ZWkYRwSw -- Snapshot at Level 93 (day 3/4ish) with pretty garbage gear https://pastebin.com/eksvMkXz -- Snapshot at Level 95 with much better, but still very affordable gear, but before Divine Flash transition

Missing min-max upgrades

1. Awakened Gems

2. +2/3 gem level Corrupted Chest

3. Nearby enemies have -chaos res helmet

4. Dying Sun

5. +2 Pierce on Boots to get better annoint

Video
Uhm, so this is the most scuffed part. I originally planned on making a full guide on this because it turned out so much better than I expected, but life and mood got in the way and I ended up quitting the league fairly early and realized today that I never even recorded any mapping footage. So I tried a last minute recording of a Phoenix map 10 minutes before the realm shut down and proceeded to die because I haven't played in so long that I forgot I can't actually reliably face tank his big explosion. On top of that, there's apparently some problem with my OBS because the resulting video seems to have only 0.3 FPS although it should have had 60 and the game ran smoothly on my 144hz monitor while recording.

So, basically the video below is virtually unwatchable, but I can't really record another one now because realm is down. However, I figured the build idea might be so unknown that you guys won't even believe it's capable of clearing maps at all if you don't see "proof". Therefore you may feast your eyes on this travesty: https://youtu.be/OHndiX48T-g

I'll try to get a watchable video out in the near future, although probably not in the next 24H since I'm fully dedicated to bringing another meme build to life for 3.20 and still have to finish the PoB.

Good luck out there Exiles, stay insane!