[3.9] Poison Cyclone CoC: Fast mapping, decent bossing, a Nightmare in Game Mechanics

Elusive (always up)
Take no extra damage from critical strikes while Elusive
Reduced damage over time taken while Elusive
Reduced damage taken while 2 or more rare/unique enemies are nearby
10k effective life
Fortify
Blind enemies
Not stationary while attacking
Immune to stun while channeling
Some Dodge
Some Evasion

Poison is an ailment that can be applied with hits, if you have a chance to poison from some source on that hit.
Poison will deal 20% of that hits physical and chaos base damage* per second as chaos damage over time.

*Base damage means poisons use the damage of a hit before applying most damage modifiers.
Any damage modifier applicabe to poisons will then be applied to the poison damage.
(The main consequence of this is, that poisons ignore modifiers to spell and attack damage.)

Base damage for spells is the damage on the gem including applicable support gem modifiers and sources of added damage.
Base damage for attacks includes the weapon damage, damage on a gem + support gems and added damage. I have another spoiler for more details on weapon damage.

So poison damage scales with stuff that affects our base damage and with stuff that obviously affects poisons. This includes:
-increased damage / damage over time / chaos damage / poison damage
-(chaos) damage over time multiplier (very strong)
-damage with ailments
-increased (chaos) damage taken (especially Despair and Withered)
-reduced chaos resistance
Attacks deal increased damage with hits and ailments will work on attacks and not on spells making it only half-effective (since we use attacks and spells).

These modifiers do nothing for us:
-spell and attack damage
-increased damage with hits
-area damage, projectile damage, …

And then there is increased physical damage, which is complicated:
Increased physical damage actually works on the part of your poison damage that was caused by physical damage (probably because PoE treats this stuff as damage conversion, but who knows).
A hit that has 100 physical damage and 200 chaos damage and is subject to 15% increased physical damage will have effectively 5% increased poison damage.

Increased poison duration will make poisons make last longer but will not change the damage per second of that poison. As an assassin we get loads of this, which is nice.
Poisons you inflict deal damage x% faster actually shortens the poison duration and increases the poison dps. You'll have effectively more poison dps and less duration.

PoB provides lots of confusing statistics with poisons. As an assassin we can end up with very long poison duration, that will not fully run through even against Shaper. The interesting statistic for our damage is Poison DPS, not total DPS or total damage per poison.
Some stuff (like Coralitos) provides unrealistically nice damage stats if you look at the wrong statistic.

Cast on Crit has a cooldown of 150ms. Due to server mechanic stuff this results in a maximum of 6.06 triggers per second which we reach if and only if we have an attack rate of exactly 6.06 attacks per second. Having slightly less attack speed is no big deal, but if you have slightly more attack speed, you'll half (!) the triggers per second. This is because you will attack every 149ms or faster, but the next CoC is only ready after 150ms.

NEVER go slightly above 6.06 attacks per second! You can double the attack speed to 12.12 attack per second and reach 2 attacks per 1 coc trigger. This requires heavy investment and is a variation-possibility for this build.

Beware of attack speed modifiers that are not active while you are in the hideout (frenzy charges, Blood Lust, increased attack speed while you are elusive) and of attack speed modifiers, that do not show in PoB (increased attack speed while you are elusive, passive tree nodes affected by timeless jewels).

For a detailed description you can find a great guide here, which I frequently used for reference:
The Cyclone Cast on Critical Strike Cooldown Guide MkIII
https://www.reddit.com/r/pathofexile/comments/e5pyr8/the_cyclone_cast_on_critical_strike_cooldown/

You can include increased cooldown recovery speed in this build allowing for higher attack rates. These come with certain thresholds due to server ticks (again for more details: check the guide above):
14% cooldown recovery speed or more: 7.57 attacks per second max
52% cooldown recovery speed or more: 10.10 attacks per second max

Beware of attack speed modifiers that are not active while you are in the hideout (frenzy charges, Blood Lust, Golems, increased attack speed while you are elusive) and of attack speed modifiers, that do not show in PoB (increased attack speed while you are elusive, passive tree nodes affected by timeless jewels).

You can probably skip this section if you have experience playing attack builds. I didn't and several mechanics did confuse or suprise me, so let me spare you some hassle.

Weapons deliver our base attack damage, base attack speed and base critical strike chance for attacks (unless we have sources of additional crit chance). Base values are shown if you hover over your weapon and are only subject to local modifiers on the weapon. The base values are afterwards affected by global modifiers. This makes local modifiers incredibly powerful, because:

Increased modifiers have diminishing returns the more you stack them, BUT you have each local modifier usually only once. Consequently it effectively acts as a more multiplier (and those are incredibly powerful).

To put it simply: 25% increased crit chance on your weapon = 25% more crit chance for attacks*
(*unless you get additional crit chance somewhere, but its great anyways)

There is one big BUT: Local modifiers do not affect our spells, since those don't use the weapon.

Bottom line: Global increased damage, attack speed and crit chance from the tree, gear etc. is nice. Local modifiers on our weapon to those stats are incredibly more powerful since they effectively act as more multipliers.
Local modifiers on a weapon do nothing for our spells.

*under construction*

Awakened Added Chaos Damage can be replaced with Unbound Ailments, not with Added Chaos Damage.
If you do not have the off-colors or a corrupted chest, Unbound Ailments, Energy Leech Support and Efficacy Support are good blue support gems.

This is the basic gear which you can get for cheap and later on upgrade step by step.
I have a Gucci-section on how to upgrade, but let's get this assassin started first.

Generally: We aim for 50:50 ES/Life and life has problems keeping up, so low ES-rolls are fine.

Timeless Jewels
Before you keep wondering why / how we combine Life and Energy Shield:This jewel is not mandatory, you can play hybrid just like that and add it later (Timeless Jewels are quite expensive at league start but will drop off later).
50% of damage bypassing ES allows us to recover ES and life simultaneously and always tank with both health pools. This is actually an advantage. Plus we get an enormous ES-boost.
This is the best place to socket it, as it comes with low travel expenses, does not delete good nodes and has easy access to the corrupted notables of Physique and Alacrity.



Helmet


Weapon

Body Armor



Shield

Boots
Gloves
Rings

Amuletts
Belts
Flasks

Jewels

The closer we get to 100% crit chance, the better. I ran around with 90% crit chance during Diamond Flask effect and was quite happy.
+x to crit chance is awesome and hard to get. This is a good point do some investing, see the spoiler above. Increased Crit chance (local) on a weapon is basically mandatory, look for a top roll if you use Whaps Nest. When you start min-maxing, aim for 95%+ crit chance.
PoB does not take into account that enemies on Consecrated Ground grant 100% increased crit chance, which we usually spread around without it being totally reliable.

100% chance to hit requires some investment but is doable. Look for Accuracy on your Weapon of choice, Rings, Amuletts and Gloves and maybe use a Tempered Mind Jewel (see gear section).
Ice Golem and Precision can be leveled flexibly depending on how much mana you have to spare/how high your CwDt setup is.

As mentioned at the start, get as close as possible to your desired attack rate and definitely don't go above (remember frenzy charges, PoB ignoring incr. Attack speed while elusive and the other stuff I mentioned). Double check if you change weapons or get increased cooldown recovery speed.

100% chance to poison is mandatory, Fenumus Toxins and our ascendancy do this (double check if you have less than 5 power charges). Maybe supplement through the tree / Poison Support Gem if you do something differently. Do not use chance to poison with attacks / with weapon xy, since this will not cap your poison chance on spells.

Aim for 0% chaos res (or more if you can get it cheaply).

Life and ES should be 1:1 and you can get 9k-10k effective life.

You need a little investment to sustain your Mana. These work on a low budget / while leveling:
a) 2 times -3 cost of channeling skills (crafting bench from Jun-Elrond)*
This is the go-to, but takes a while to get in your bench.
You can buy a ring with this enchanted on it or ask someone you buy from if he can craft it for 5 extra chaos.
b) Lucidity notable in the tree (NOT effective use of your skill points. Valid while leveling or if you couldn't yet get your hands on another option)
c) Enduring Mana Flask (doesn't end on full mana, only during leveling, flasks are too important)

If you are willing to do some investment:
c) Mana gain on hit on your Claw base (after you replace Whasp's Nest and if you can find/craft a good one. For me this is the gold standard.)
d) 2 Mana gained on hit on abyss jewels*
e) Mana regen* (boot enchant, usually not worth it on jewellry)
*Maybe combine with a).

This is the tree and my PoB link.

https://pastebin.com/cRsU4w7R


Bandits, Pantheon, Enchantments
Kill all bandits (or help Alira on a budget or as a temporary choice for leveling)
Soul of Arakaali for reduced damage over time is my preference.
Soul of Lunaris for Dodge, Avoidance and phys mitigation is good, too.

Soul of Shakaari for Poison Immunity because of Hunter influenced areas.
Soul of Ryslatha is nice in lab or for long bosses while your damage isn't insane yet. Since it's the only other minor god with a noticable effect, it's also my recommended alternative if you don't care about poisons.

The usual stuff. I used Thief's Torment until mapping,it's really nice.

The Princess is a good leveling weapon if you don't care to update rares regulary.

Passive Tree: Skip life, ES, jewels, the corrupted section of your future glorious vanity.

If you need attack speed for some strange reason:

I somehow missed out on Awakened Deadly Ailment Support giving Poisons inflict damage faster, get it!