General idea:

Storm's Gift gloves proliferate shock on death, which keeps our Herald of Thunder going. Herald of Thunder has 100% chance to ignite with Stormfire ring, and ignite proliferation to spread the burn so we just keep running around, and Herald goes as long as we have enemies.

Lone Messenger gives more damage on the hit, and more damage over time, so it actually gives 150% more damage overall. Kind of insane.

Arcane Cloak + Withering Step give great defensive bonuses that work while Herald is bombing because Herald doesn't count as using a skill. Free Elusive buff, basically.

Lasting Impression is a medium cluster notable for 80% increased damage over time, nothing special, just really efficient for a single point.

Circle of Regret, HoT enchant, Heraldry are things that lower our mana reservation of Herald of Thunder, all the way to 0%. This keeps us able to have all of our mana (to use for MoM)

Scorching Ray can be casted while Herald is bombing for even more single target damage & fire exposure.

2x Writhing Jar is used to make sure we have worms to kill to keep the Herald up incase it drops.

I played this build as a Trickster, after 95 levels it kind of dawned on me that Heirophant is probably better, but I'm burning out from PoE and not going to reroll it right now. It clears extremely fast due to Elusive, Rotgut (we get frenzy charges from Trickster) and never needing to stop moving. The single target is lackluster, especially vs bosses that phase (because our Herald will drop). It has dodge/spell dodge cap, and roughly 7k eHP with MoM so it is fairly safe. And to top it off, it's an off-meta DoT build, so it's very inexpensive compared to most builds.

PoB: https://pastebin.com/eeVkJ0T5