I wanted to mess around with Hexblast since it was announced but stayed away after some initial reviews. The new Blackflame unique along with damage effectiveness boost to Hexblast re-ignited (yeah I went there) my interest. I took some guidance from different places including Mathil, SmashinBob, Zyememe and poe.ninja.

I know reddit attention span is short, so feel free to skip ahead to the list, but I tried to cover everything I've tried so far. Lmk if PoB doesn't work, I also have notes on the gear in there. PoB: https://pastebin.com/KZzmmxia

Anyway, I wanted to get some more eyes on this build/tree. Right now I am doing Guardians averaging <1 deaths and can do their invitation (a couple deaths) on a 5-link and about 100c in gear. Most of that is in clusters, 5L Carcass Jack, and Intuitive Leap (which I might drop anyway). I can full clear juiced delirious maps with an Obliteration added for QoL, so far up to 40% now. I was able to get A5 to last phase on a 5L but I suck at that fight so I wasn't able to finish it, unfortunately. Will try again with a 6L.

The basic damage loop is: self-cast a curse (enfeeble or temp-chains), wait 0.04s-1.44s to accumulate up to max doom. Vixen's Entrapment also casts Despair + Vulnerability + another defensive curse (enfeeble or temp chians). Cast Hexblast. Hexblast hits, removes self-cast curse, and ignites the enemy which takes burning damage as chaos. Impending Doom support procs Doom Blast which hopefully crits, procing Elemental Overload. The hits re-apply the initially self-cast curse, at a lower effectiveness from an on-hit source for full up-time. Damage is boosted by increasing burning damage and chaos damage taken.

I am now thinking this could be a very viable league starter, so I am not trying to scale gear, since there are some very obvious upgrades. While technically a 2-button build, it feels significantly smoother than my BF/BB starter, due to naturally high cast speed.

The build is rather defensive (40k Max hit) due to self-cast Enfeeble/temp chains boosted by 40 doom, temp chains/enfeeble on hit, sand stance, endurance charge generation with Enduring Composure, CWDT + Immortal Call + Stone Golem, easy positive chaos res due to Occultist's Withering Presence, some block chance, elusive from Withering Step, more blind Disorienting Display and Smoking Remains, and Fortify from Shield Charge. I also can keep my distance until after enemy is weakened, and mobility is high. No defense is truly maxed out, but there's many layers. This is partly due to not really needing many sockets for damage -- that mostly comes from tree, gear, and gem levels. The other reason for so much defense is the crap gear I am forcing right now. Dropping Flesh and Stone for Skitterbots didn't feel as good, but could boost damage.

A couple of issues I am not sure about:

1. Not enough EO uptime. I have self-cast Enfeeble with Increased Critical Strikes + Impending Doom support, but the game does not indicate this is supported by ICC by highlighting its socket.

2. Ways to achieve similar results by cutting down on some cluster jewels to make things cheaper

3. Any obvious damage oversights. I haven't decided if stacking curse effect is the play here, and I've opted not to do that since its only ever a couple percent per passive point. See thoughts on wither below. Besides Despair and -chaos res to nearby enemies from ascendancy, there's really not any other way to reduce enemy chaos resistance (Hunter helm I assume is expensive early in league). Wither is the only way I know to increase chaos damage taken (Malediction too but can't scale?). The other damage scaling is fire/burning damage, fire DoT, ignite duration, of which there are plenty of different places to get that. PoB suggests that added chaos damage on initial hit isn't the play compared to fire/burning damage buffs.

4. Is lvl 4 Stone Golem worth it? Other options? Chaos Golem?

5. Ailment immunity would be nice but I don't see an obvious way to get it.

6. any other thoughts!

As long as Blackflame remains in the game and pretty cheap, I think this is a pretty viable league start.

Extra Theory and ramblings for the interested:

The way I understand it, the reason this build works so well, especially on uniques/bosses is that the reduced effect of curses is counteracted by Doom gain and the fact that damage is scaled by Wither, since burning damage is taken as chaos damage. Wither does not have decreased effectiveness against any monster type. Also, we can safely assume that Wither is at max stacks because it does not expire while the enemy is ignited and we also get increased Wither duration when going for 20% increased Wither effect on the Corruption notable. We get wither from Occultist ascendancy, Withering Step, and Wither Totem for back up. So, fire/burning damage modifiers boost damage that is "dealt" up front while low chaos, wither, and Malediction boosts damage taken on the back end (up to 124% incr chaos damage taken). Also ignites last a long time due to temp chains.

Self-casting Despair, in theory is stronger because 40 doom will increase its effectiveness by 40%, but in practice having to cast, blast, then cast again is clunky. At most it gives another 10% incr damage taken from an extra -4% chaos res. I will play with this more. There is a version of the build that uses Anomalous Flammability for 50 doom and being able to trade Combustion for Hypothermia + Skitterbots, and that might be where this build ends up in its expensive form.

I've seen temp-chains on blasphemy, but tried it and didn't find it necessary for mapping since its smooth already. Temp-chains on blasphemy is slightly more defensive and turns mapping into a 1-button experience, so its definitely an option if you can get a hold of Solstice Vigil. This leaves a gem slot for Flesh & Stone, so its a preference thing.

I don't take Doomsday because things just move around too much. With mobs on temp chains along with other defenses I can usually run around for the 1.44s it takes to reach max Doom and not have to worry about where I placed the hex, and I can spam Hexblast right after applying curse while mapping which is plenty of damage.

With a curse on hit anywhere in the build, that curse will be the one we self-cast since it is automatically reapplied when Hexblast hits (using Enfeeble now). While do-able, Despair or Vulnerability on hit are sub-optimal for DPS since a high level gem has higher curse effectiveness; going for enfeeble or temp chains on hit is preferable.

We can do most map mods including reflect. The only one that doesn't feel good is ailment avoidance for obvious reasons. Its "doable" if there's no other option but you have to spam the heck out of Hexblast to get an ignite to stick.

I might drop Profane Bloom for Vile Bastion for more comfortable bossing (stun immunity), but I love those pops.