So I decided to do something I thought I'd never attempt - explain poison damage on this forum (I knew I'd regret this)... This guide is not pretty and it's not really accurate, but it will explain the basics.
This guide in not correct for Poison skills. These have their own calculations (and are already explained by people that bothered to write their guides, and there is no point in copy-pasting their efforts). Just use search and read them first-hand.
Let's see, you have a bunch of items that add poison damage, but no idea how they work together? Read on.
~~~~~~Important thing #1:
Everything that gives poison damage is called a source
If you have 2 poison charms, 2 emeralds, Tal rune and a poison jewel, that's 6 sources of poison damage. If you could socket all of them in a plain white bow, the bow would have 7 independent
sources of damage.
When you attack, all of these sources combine into a single big poison damage.Important thing #2:
Poison doesn't do damage "per second", it does damage "per frame". Every second has 25 frames in it, so a source that says "over 6 seconds" actually means "over 150 frames". When calculating poison damage, always convert seconds to frames.Important thing #3:
The damage that poison does each frame, is called damage per frame
(duh). To see how much damage your source does each frame, divide the total damage by the number of frames it's active (think of it as damage per second, but more accurate). This determines whose poison is damaging the monster (the highest total damage per frame overwrites any active poison damage your party members are doing, and cannot be overwritten).
Example: Foul small charm has "+50 poison damage over 4 seconds". That means it is a source of damage, that does 50 total damage over 100 frames. The damage per frame is 50/100 = 0.5
So, the most important thing about every poison source is: how many frames is it working
, and what damage does it do each frame
How do you calculate the total damage of all sources? You add the damage per frame
together, and average the duration
2 emeralds (100 poison damage over 7 seconds, each)
Tal rune (75 poison damage over 5 seconds)
Foul Small Charm (50 poison damage over 4 seconds)
Pestilent Small Charm (175 poison damage over 6 seconds)
Jewel of envy (20 poison damage over 2 seconds)
Take that bow and say:
The first source (first emerald) does 0.5 damage per frame, for a duration of 175 frames.
The second source (second emerald) does 0.5 damage per frame, for a duration of 175 frames.
The third source (Tal rune) does 0.6 damage per frame, for a duration of 125 frames.
The fourth source (first charm) does that damage per frame, for a duration of so many frames.
Do that for every source you have (I leave it as an exersise to the reader).
Now take all the damages per frame and add them together. That is (0.5 + 0.5 + 0.6 + ...), which would be the total damage per frame
that your attack is doing.
Now take all the durations and average them. That is (175 + 175 + 125 + ...)/6, since we have 6 sources of damage. The average number is the total duration
of your combined poison attack.
So you are doing 3.6 damage per frame, for 129 frames. In game terms, that is 464 damage over 5 seconds (3.6*129 damage over 129/25 seconds).
~~~~~~How do we increase the damage?
What damage? Damage per frame, or total damage?
Damage per frame means how fast the poison removes life. Total damage means how much life will the target lose if the poison runs its full course.
You can increase speed by adding items that have low poison duration, because it will make the average number of frames smaller. The total damage in this case wil decrease, but the poison will kill faster. This is good if you prefer to keep beating the poor monster till it collapses. (=works better with fast attacks)
You can increase the total damage by adding items with same or higher duration. This will give you the same or slower speed, but will increase the damage over time. This is good if you want to hit Diablo once and go make some coffee while Diablo is slowly dieing. This is also good if you want to stop monster regeneration. (=works better with slow attacks)
~~~~~~How are the poison affixes calculated? And are they separate sources?
Say, the 451 damage small charm. It is a "Pestilent small charm of Anthrax", almost the most potent source of poison damage in the game (skills excluded).
Pestilent and Anthrax combine into a single source, meaning that the charm is not counted as having two sources. Same goes for a magic bow etc, that has two poison mods on it's own (if you put an emerald in such a bow, it becomes two sources, the bow and the emerald).
The damage of such charm (or bow or whatever, with their own possible affixes) is calculated this way:
Pestilent +175 Poison Damage Over 6 Seconds (1.1 damage per frame, for 150 frames)
Anthrax +50 Poison Damage Over 6 Seconds (0.3 damage per frame, for 150 frames)
Add damage per frame together, add duration together.
The total damage per frame is (1.1 + 0.3)= 1.4
The total duration is (150 + 150) = 300 frames - we don't do average here
The final damage is 1.4*300 = 420, over 300/25 = 12 seconds.
Now, the game says 451 iirc, not 420, that's because of the way the game rounds up/down the decimals. I truncated them into easy to use numbers.
The damage is generally rounded up, while duration in frames is rounded down. If you want more accurate calculations, try searching for Tao of Poison by BKelly (but don't come to me crying