PoB for testing: https://pobb.in/tAnsd5eh8vjN
Hope this helps demystify poison damage a little bit!
0:00 Intro and basic poison calculation
1:40 You still need poison chance!
2:14 Example PoB setup
3:11 How split damage types work for poison
Life
57
Mana
51
Energy Shield
0
DPS
986
Effective Hit Pool
36.24
Phys Max Hit Taken
57.00
Chaos Res
-60
Fire Res
-60
Cold Res
-60
Lightning Res
-60
Armour
0
Evasion
16
Block
undefined | undefined
Crit Chance
6%
Crit Multi
150%
Rage
0
Strength
14
Intelligence
23
Dexterity
23
Ward
0
Item Quantity
0%
Item Rarity
0%
Movement Speed
0%
