Poison damage explained
Poison is by far the most complicated damage type in the game (of which there are 6). There have been a lot of questions regarding poison skills in median. In order to decrease the amounts of posts asking about poison skills, I made this post in which I'll try to explain every poison skill in the game. So here we go:
A list of all poison skills in the game:
Amazon:
Hyena Strike: Passive poison damage
Curare: Passive poison damage
Assassin:
Twin Fang Strike: Spell poison damage
Way of the Spider: Passive poison damage
Scorpion Blade: Active poison damage
Barbarian:
Snake Stance: Passive poison damage
Druid:
Plague avatar: Spell poison damage
Poison flash: Spell poison damage
Acid fiends: Minion poison damage
Necromancer:
Angel of Death: Active poison damage
Rotting Flesh: Spell poison damage
Pestilence: Spell poison damage
Paladin:
Symphony of Destruction: Spell poison damage
Plague: Passive poison damage + Minion poison damage
Sorceress:
Lorenado: Spell poison damage
Miasma: Spell poison damage
Carpet of Spiders: Spell poison damage
Hive: Spell poison damage
Important poison facts:
Those are all the poison skills in the game. Before we try and figure out what the difference between each type is, let's first understand the similarities:
1. Poison duration does not affect poison damage per second. In other words, if you do 100 damage per second over 10 seconds, your total damage would be 1000. If you add 5 more seconds, your damage per second won't decrease to 66 (1000:15=66). Instead you will do 1500 total damage (100*15=1500). This is a very good thing that many people don't understand so they try to avoid increased duration. The truth is, it can really help if you want to kill an enemy in 1 hit.
2. Poison damage doesn't stack. If you hit an enemy with an attack that does 100 damage per second, twice, you won't do 200 damage per second. What actually happens is that the highest damage per second is applied.
Example:
You cast gamma field that has a duration of 20 seconds, it rolls for the damage 8 times in this order-
100, 250, 70, 400, 200, 100, 68, 365.
The damage that will be applied is 400, because it's the highest damage per second. The total damage would be 400*20=8000. This also includes changes in the monsters resist. If you poison a monster that has 50% poison resist, then decrease the resist to 0, the poison damage will increase by 50%. This also works very nice in uberquests because even if an enemy turns immune, it will still continue to take damage if it was damaged before becoming immune (this strategy is usually used with gamma field).
3. Poison damage is the only element that triggers on kill procs.
Types of poison damage:
Now that you know the basics of poison damage, we can get into more detail about the types of poison damage.
Spell poison damage:
This type of poison damage is fairly simple.
affected by-
+spell/poison damage
+skills
+poison duration.
Energy and Energy Factor / Strength Factor
not affected by-
+x to poison damage over y seconds
weapon damage multiplier.
Passive poison damage:
Passive poison damage includes all the skills that passively add poison damage to your attacks. Poison damage added from items works in the same way.
affected by-
+spell/poison skill damage (only in melee, see note)
+skills (if it's a skill and not on an item)
weapon damage multiplier
+x poison damage over y seconds.
not affected by-
+poison duration
+spell/poison skill damage (only with missiles, see note)
Energy and Energy Factor / Strength Factor
Even though it is not affected by poison duration, there still is a way to increase the duration of those skills-
The interesting thing about passive poison damage is when there is more than one source of it. What happens then is that the damage per second is added and the duration is added, and then averaged.
Example:
Your snake stance does 100 poison damage per second over 5 seconds.
You have a pair of gloves that do 10 poison damage per second over 9 seconds. First you add the damage per second=100+10=110. Then you add and average the duration = (5+9):2 = 7. Now in order to calculate the total damage, all you need to do is 7*110=770. As you can see, the not so impressive gloves, increased our total poison damage by 54%.
Note: This type of poison damage has different mechanics depending on the type of attack. What happens is that when this poison damage is applied with missiles, it is not affected by +spell/poison damage. But when used in melee, it is affected by +spell/poison damage. Also it's important to understand that the nova on retaliate (or any other nova attack) is considered a missile, aswell as the rocks on shower of rocks, and the spikes on crucify.
Active poison damage:
This is probably the weirdest thing about poison. Only 2 skills in the game are using the "Active poison damage" (yes I made up the name). That skills are: Scorpion Blade and Angel of Death. What happens with them is simple- you don't average the duration.
affected by-
+spell/poison skill damage (only in melee, see note)
+skills
weapon damage multiplier
+x poison damage over y seconds.
Energy and Energy Factor / Strength Factor
+poison duration
not affected by-
+spell/poison skill damage (only with missiles, see note)
Example:
Your scorpion blade does 100 poison damage per second over 5 seconds.
You have a pair of gloves that do 10 poison damage per second over 9 seconds. Like in most cases, you first add the damage per second (=110). But, unlike most cases of passive poison damage, you don't average the duration, you just add it. So the total damage would be: 110*14=1540.
I'm not sure about this, but it seems like the game displays snake stance's damage as if it was Active poison damage, even though it's passive.
Minion poison damage:
The simplest type of poison damage. Since this is not really your damage, nothing that affects you will affect the damage of your minions. So +poison duration, +x poison damage over y seconds, +spell/poison damage don't affect it. The only things that do affect it are the things that affect your minions. These include synergies/+skills, elemental totem, mark of the wild, acid fiend's aura and so on. The only exception to this are the acid fiends. These gain your characters own poison spell damage.