tl;dr CI HoT Autobomber with Herald of Ice pops and Crest of Desire. My first mostly-self-made build, though it borrows better players' concepts (such as CWDT Crackling Lance). Note: the build is very vulnerable to oneshots and so not good for XP gain.

About My Herald of Thunder Autobomber

My build functions by using a decent Crest of Desire helm to add 100% more damage, +8 gem levels and ~40% hit frequency to Herald of Thunder, saving mana reservation to do a 4L Herald of Ice for clear and a Discipline aura. I use (i) two large clusters and a cold damage Light of Meaning, (ii) the "freeze duration" cold mastery ~~and Brine Bound Ascendancy notable (1s min freeze duration)~~, and (iii) 6L CWDT Crackling Lance to provide big shocks (usually 50-60%) to prop up single target DPS.

I enjoy how weird Crest of Desire (shoutout to Mathil's Tornado build from a while back) is, so I wanted to make this build work with that item while the autobomber mechanics are so accessible in this event. Objectively better builds have been posted here, but I wanted to share mine in case any other Celestial Herald Effect MTX enjoyers want out from under the thumb of Big Inpulsa.

Budget: probably 15-20 divine. I upgraded incrementally so it didn't feel expensive. Big-ticket item is a Crystal Belt with 154 ES, 109% resists, and crafted 17% damage - have you checked in on Rog lately?

Pros

• MTX-enhanced Herald of Ice pops
• 10 Hz hit rate!
• Cheap to get started - I started with +7/40% helm and 2x rings
• Keep body, glove slots for rare gear
• Guaranteed crits
• Helmet provides most of the damage
• Get to use aura(s) due to no Lone Messenger
• Surprisingly okay single target DPS

Cons

• Can't see shit due to MTX-enhanced Herald of Ice pops
• 10 Hz self-hit rate...
• Defense layers: freeze, ~4.5k ES, portals - very vulnerable to oneshots
• Lose ~~Heatshiver~~helm slot
• Lower HoT damage ceiling than other similar builds
• Terrible handful-of-targets DPS
• Getting enough ES for leech to feel good won't be cheap

Learnings from my first build, other thoughts

• "The damage inflicted by this skill is not affected by modifiers to spell damage" is a lot more all-encompassing than I thought. Finding ways to boost HoT DPS was a fun puzzle.
• Getting enough ES so 10% instant leech offsets 10 Hz self-hits was not easy. My body armour and belt carry my ES hard, allowing me to put a couple points into damage and AoE.
• I started with hybrid life/ES, Petrified Blood, and Corrupted Soul, but had a difficult time solving chaos damage while keeping fire/cold/light resistance capped. I decided to bypass this by just going CI; my ~1.5k chaos max hit rose to 5k phys max hit. This is a buff.
• I tried an ES gain on hit Watcher's Eye and it didn't feel like it was doing much.
• I was too lazy to try CWDT Immortal Call (too much strength required) or to get more reservation efficiency to use Flesh and Stone. Also I did not quality many of my gems or get awakened supports as they would not improve HoT's DPS.
• I feel like there is probably a good Thread of Hope or Impossible Escape I could use to eke out more damage, but I am probably moving on before I figure it out.
• Crest of Desire gives a lot of extra hit rate, which would theoretically open up a ring slot for e.g. Polaric Devastation, Circle of Ambition, etc.
• I could have bought XP carries to get a few more points (either into the Light of Meaning or over to my anointed notable so I could anoint another), but am too lazy. Similarly, I was too lazy to buy a good Vaal Discipline gem.
• Overall I had a ton of fun tinkering with this without a guide and am surprised it even got to T16.

Current PoB link

(assumes. 5s freeze boost, 50% shock, 30% chill)

Videos (unflattering but more realistic one first)

T16 Beach [feat. oneshot]

T16 Ashen Wood

T16 Lighthouse

Very boring Chayula Breachstone [feat. 64% shock on the boss]

edit: why am I chugging a life flask? This was my solution to Corrupted Blood and bleed that was leftover from my leveling build... have we established that I'm lazy yet?

edit2: updated pobb.in to reflect a flask change not captured by the original.

edit3: updated pobb.in to ditch two nonfunctional masteries leftover from the life/ES build; net gain of ~2.5% DPS and some AoE.

edit4: ditched reservation cluster (it was providing mostly aura effect, which is not huge for this build) and two AoE nodes to path to Frost Walker. Net gain ~5% dps over the version in the video, net loss of some mana and ~100 ES.

edit5: changed Brine Bound Ascendancy notable to Glacial Wave for ~15% more damage and some survivability. Thanks u/byzz09!