Guide:Calculating Poison Damage v1.10, by onderduiker

Some (if not all) of what follows may already be known, but to the best of my knowledge it hasn't all been collected in one place on this site. Bkelly's The Tao of Poison was an excellent source of information about poison damage for v1.09, but there are a number of changes in Diablo II: Lord of Destruction v1.10+ and the Tao hasn't been updated.

I've also posted Poison damage calculator.xls, a Microsoft Excel worksheet, in the Diablo Files forum of the Diablo III Community Forums. Even if you know how to calculate poison damage, this should make it easier.

Diablo II Strategy Guide Info:

[edit]

• Patch: v1.10
• Gametype: PvE/PvM and PvP
• Guide Topic: Poison damage
• Class: Amazon, Assassin, Barbarian, Druid, Necromancer, Paladin, Sorceress
• Author: onderduiker
• Related Article(s): Poison damage calculator.xls, The Tao of Poison

Introduction

While damage is displayed in points and length in seconds, both are calculated and applied using more precise units of measurement. Damage is calculated and applied in bits, and length in frames.

Damage		Length
Points	Bits	Seconds	Frames
1	256	1	25

Poison damage is displayed as the total damage applied over a length of time, but it's calculated by applying a bit rate (bit damage per frame) for a specified number of frames: a Toxic Small Charm applies 205 bit rate for 125 frames, which is displayed as 100 Poison Damage Over 5 Seconds (205*125/256 over 125/25).

Poison damage from multiple attacks doesn't stack. If a target is already poisoned, then the rate and length of that poison will be overwritten by that of any subsequent attack which has an equal or greater rate. Rates are compared after all modifiers have been applied.

When players, hirelings or pets apply poison to a poisoned monster, their poison is applied for one frame instead of the current poison: if their poison has an equal or greater rate, it then overwrites the current poison and it gets applied for its length; if their poison has a lower rate, the current poison then continues for its remaining length. Rates are compared after all modifiers have been applied.

When monsters apply poison to a poisoned player, hireling or pet, their poison is applied for one frame as well as the current poison: if their poison has an equal or greater rate, it then overwrites the current poison and it gets applied for its length; if their poison has a lower rate, the current poison then continues for its remaining length. Rabies and Poison Creeper can also apply additional frames of poison damage when applied to more than one monster.

A monster's damage regeneration is stopped if at least one bit of poison damage is applied per frame: monsters won't turn green if less than one bit of poison damage is applied per frame. Poison damage can kill monsters, hirelings and pets but will only reduce players to 1 hit point (although poison damage from a subsequent attack would kill them if they remained on 1 hit point).

Items

If a single item has both a prefix and a suffix applying poison damage, then the rates and lengths of both are simply added.

Small Charm	Displayed damage	Bit rate		Frames
		Min	Max
Toxic Small Charm	100 Poison Damage Over 05 Seconds	205	205	125
Small Charm of Anthrax	50 Poison Damage Over 06 Seconds	86	86	150
Toxic Small Charm of Anthrax	313 Poison Damage Over 11 Seconds	291	291	275

Displayed damage is rounded to the nearest point, although it should always be rounded down. When multiple items applying poison damage are equipped, then the rates are added and the lengths are averaged.

Item	Displayed damage	Bit rate		Frames
		Min	Max
Toxic Small Charm of Anthrax	313 Poison Damage Over 11 Seconds	291	291	275
Blackbog's Sharp Cinquedeas	488 Poison Damage Over 10 Seconds	500	500	250
Perfect Emerald	100 Poison Damage Over 07 Seconds	143	143	179
Total		934	934	704

Frames	= [704/3]
	= 234

Thus 853 poison damage is applied over 9.36 seconds (934*234/256 over 234/25). Bits and frames are the smallest units of measurement, and so calculations are rounded down to the nearest bit and frame. Gems, jewels and runes all count as separate items, even if they're socketed in a single item.

ERROR: Length is calculated differently when multiple items applying poison damage are used with skills that apply a fraction of weapon damage. This applies to the following following skills:

• Multiple Shot
• Strafe
• Blade Sentinel
• Blade Fury
• Blade Shield

Two items will apply poison damage over the sum of their lengths, while three or more items will just apply poison damage over the longest length of any of those items.

• Poison damage items

Skills

Poison damage skills add bit rate with every additional skill level. The bit rate added also increases beyond certain skill levels. Some skills also add length with every additional skill level, although the increase is linear. Others are synergised by other skills, which apply a percentage increase to bit rate dependent on the number of skill points invested in the synergy skill(s). Skill level is set at the point the player uses the skill. Adding or removing skill bonuses won't have any effect on rate or length if there's a delay between using the skill and applying the poison.

Skill	Bit rate							Frames		Synergy
	/Level	1	2-8	9-16	17-22	23-28	>28	1	2+	Skill	+%
Poison Javelin (Pn)	Min Max	32 48	+16 +16	+32 +36	+48 +52	+64 +68	+96 +84	200	+50	Pe	12
Plague Javelin (Pe)	Min Max	80 128	+48 +48	+96 +96	+160 +160	+320 +320	+480 +480	75	+10	Pn	10
Poison Dagger (PD)	Min Max	36 80	+20 +20	+30 +30	+40 +40	+46 +46	+52 +52	50	+10	PE PN	20 20
Poison Explosion (PE)	Min Max	128 384	+32 +32	+64 +64	+96 +96	+128 +128	+160 +160	50	+10	PD PN	15 15
Poison Nova (PN)	Min Max	224 400	+64 +64	+80 +80	+128 +128	+192 +192	+224 +224	50		PD PE	10 10
Poison Creeper (PC)	Min Max	12 16	+7 +7	+12 +12	+15 +15	+17 +17	+19 +19	100
Rabies	Min Max	48 112	+32 +32	+40 +40	+56 +56	+88 +88	+128 +128	100	+10	PC	18
Venom	Min Max	1,536 2,048	+384 +384	+512 +512	+640 +640	+768 +768	+896 +896	10

ERROR: Level >36 Poison Javelin displays higher minimum than maximum damage because the minimum bit rate added per level for level >28 is higher than the maximum bit rate added. When this occurs, the minimum damage becomes the maximum and the maximum damage becomes the minimum.

Level 30 Poison Dagger applies the following:

Frames	= 50+(10*(30-1))
	= 50+290
	= 340

Min bit rate = 36+(20*7)+(30*8)+(40*6)+(46*6)+(52*2) = 36+140+240+240+276+104 = 1,036 Min damage = 1,036*340/256 = 1,375

Max bit rate = 80+(20*7)+(30*8)+(40*6)+(46*6)+(52*2) = 80+140+240+240+276+104 = 1,080 Max damage = 1,080*340/256 = 1,434

Thus 1,375-1,434 Poison Damage Over 13.6 Seconds is displayed. Fully synergised level 30 Poison Dagger (20 points each in Poison Explosion and Nova) has +800% (20*(20+20)) applied to its rate:

Min bit rate = 1,036*(100+800)/100 = 1,036*9 = 9,324 Min damage = 9,324*340/256 = 12,383

Max bit rate = 1,080*(100+800)/100 = 1,080*9 = 9,720 Max damage = 9,720*340/256 = 12,909

Thus 12,383-12,909 Poison Damage Over 13.6 Seconds is displayed.

Skills and items

Most skills are treated as separate sources of poison damage whose rates (and accompanying lengths) compete with those of other skills and items. However, Poison Dagger and the javelins (but not the clouds) of Poison and Plague Javelins combine the skill's rate with any item rates. Length is calculated by summing skill and item lengths and dividing by the number of items.

Source	Displayed damage	Bit rate		Frames
		Min	Max
Toxic Small Charm of Anthrax	313 Poison Damage Over 11.0 Seconds	291	291	275
Blackbog's Sharp Cinquedeas	488 Poison Damage Over 10.0 Seconds	500	500	250
Perfect Emerald	100 Poison Damage Over 07.0 Seconds	143	143	179
Level 30 Poison Dagger	12,383-12,909 Poison Damage Over 13.6 Seconds	9,324	9,720	340
Total		10,258	10,654	1,044

Frames	= [1,044/3]
	= 348

Min damage = 10,258*348/256 = 13,944

Max damage = 10,654*348/256 = 14,482

Thus 13,944-14,482 poison damage is applied over 13.92 (348/25) seconds.

If the only item used were Blackbog's Sharp Cinquedeas, 9,824-10,220 bit rate for 590 ((250+340)/1) frames would apply 22,641-23,553 poison damage over 23.6 (590/25) seconds. Although the rate is lower with only one item, the length can be significantly longer and results in far more damage from a single stab.

Venom

Venom's rate is applied to any weapon's attack made between its casting and expiration, and adds to any rate applied by items. However, its 10 frame length overrides those of any items.

Source	Displayed damage	Bit rate		Frames
		Min	Max
Toxic Small Charm of Anthrax	313 Poison Damage Over 11.0 Seconds	291	291	275
Blackbog's Sharp Cinquedeas	488 Poison Damage Over 10.0 Seconds	500	500	250
Perfect Emerald	100 Poison Damage Over 07.0 Seconds	143	143	179
Level 15 Venom	305-325 Poison Damage Over 00.4 Seconds	7,808	8,320	10
Total		8,742	9,254	10

Min damage = 8,742*10/256 = 341

Max damage = 9,254*10/256 = 361

Thus just 341-361 poison damage is applied over 0.4 (10/25) seconds.

However, Venom's length does not override those of the skills Poison Dagger and Poison and Plague Javelins. Casting Venom can thus significantly increase the rate applied by these skills while not reducing length. Since Venom effectively creates a single source which sums the rates of Venom and items but which only applies for Venom's length, the length is the sum of the skill length and that of Venom.

Source	Displayed damage	Bit rate		Frames
		Min	Max
Toxic Small Charm of Anthrax	313 Poison Damage Over 11.0 Seconds	291	291	275
Blackbog's Sharp Cinquedeas	488 Poison Damage Over 10.0 Seconds	500	500	250
Perfect Emerald	100 Poison Damage Over 07.0 Seconds	143	143	179
Level 30 Poison Dagger	12,383-12,909 Poison Damage Over 13.6 Seconds	9,324	9,720	340
Level 15 Venom	305-325 Poison Damage Over 00.4 Seconds	7,808	8,320	10
Total		18,066	18,974	350

Min damage = 18,066*350/256 = 24,699

Max damage = 18,974*350/256 = 25,941

Thus 24,699-25,941 poison damage is applied over 14 (350/25) seconds. Classes other than the Assassin can gain the ability to cast Venom by equipping certain items, which allow it to be cast by various methods.

Item	Source	Duration (seconds)	Bit rate		Frames
			Min	Max
Arachnid Mesh Spiderweb Sash	Level 3 Venom (11 Charges)	128	2,304	2,816	10
Andariel's Visage Demonhead	Level 3 Venom (20 Charges)	128	2,304	2,816	10
Treachery 'ShaelThulLem' Armor	25% Chance to Cast Level 15 Venom on Striking	176	7,808	8,320	10
Grief 'EthTirLoMalRal' Sword/Axe	35% Chance to Cast Level 15 Venom on Striking	176	7,808	8,320	10
Dragon 'SurLoSol' Armor/Shield	20% Chance to Cast Level 18 Venom When Struck	188	9,600	10,112	10
Rainbow Facet Jewel	100% Chance to Cast Level 23 Venom When You Level-up	208	12,928	13,440	10

+% Poison Skill Damage

+% Poison Skill Damage is gained by equipping certain items and applies a percentage increase to the rate which is multiplicative with any synergies. It's also applied to the rate from items when applied with mêlée weapons, but not when applied with ranged weapons.

The point at which +% PSD is applied varies for each skill, although it is not applied to Poison Creeper. For more details about the mechanics of each skill, see the individual skill descriptions.

Skill	Point of application
Poison Javelin	Javelin: throwing Clouds: creation
Plague Javelin	Javelin: throwing Clouds: creation
Poison Dagger	Striking
Poison Explosion	Casting
Poison Nova	Casting
Rabies	Bite: striking Contagion: creation
Venom	Casting

Equipping Trang-Oul's Claws Heavy Bracers applies +25% PSD to level 15 Venom when cast:

Min bit rate = 7,808*(100+25)/100 = 7,808*1.25 = 9,760

Max bit rate = 8,320*(100+25)/100 = 8,320*1.25 = 10,400

Source	Displayed damage	Bit rate		Frames
		Min	Max
Toxic Small Charm of Anthrax	313 Poison Damage Over 11.0 Seconds	291	291	275
Blackbog's Sharp Cinquedeas	488 Poison Damage Over 10.0 Seconds	500	500	250
Perfect Emerald	100 Poison Damage Over 07.0 Seconds	143	143	179
Level 15 Venom	305-325 Poison Damage Over 00.4 Seconds	9,760	10,400	10
Total		10,694	11,334	10
Level 30 Poison Dagger	12,383-12,909 Poison Damage Over 13.6 Seconds	9,324	9,720	340

+25% PSD is now applied:

Min bit rate = (10,694*(100+25)/100)+(9,324*(100+25)/100) = (10,694*1.25)+(9,324*1.25) = 13,367+11,655 = 25,022 Min damage = 25,022*(340+10)/256 = 34,209

Max bit rate = (11,334*(100+25)/100)+(9,720*(100+25)/100) = (11,334*1.25)+(9,720*1.25) = 14,167+12,150 = 26,317 Max damage = 26,317*(340+10)/256 = 35,980

Thus 34,209-35,980 poison damage is applied over 14 (350/25) seconds. +% PSD can only be found on the following items:

Item	+% PSD
Rainbow Facet Jewel	3-5
Trang-Oul's Claws Heavy Bracers	25
Bramble 'RalOhmSurEth' armor	25-50

Lower Resist

A target's Poison Resist (PR) % reduces poison's rate, and PR 100+% makes a monster Immune to Poison (players and hirelings are capped at PR 95%). Lower Resist (LR) applies PR -%, although it's applied at 1/5 effectiveness against Immune to Poison monsters: level 10 LR's PR -55% is reduced to PR -11% (55/5). PR -100% is the absolute minimum to which a target can be reduced, doubling the rate.

25,022-26,317 bit rate for 350 frames results in 34,209-35,980 poison damage being applied over 14 seconds to a target with PR 0%. PR 50% would halve the rate, but casting level 10 LR (PR -55%) results in the following:

Min bit rate = 25,022*(100-(50-55))/100 = 25,022*1.05 = 26,273 Min damage = 26,273*350/256 = 35,920

Max bit rate = 26,317*(100-(50-55))/100 = 26,317*1.05 = 27,632 Max damage = 27,632*350/256 = 37,778

Thus 35,920-37,778 poison damage is applied over 14 (350/25) seconds. LR is applied when the target is poisoned, so it can be overwritten by another curse immediately afterwards. Even if LR is required to break immunity, once poison has been applied its rate and length remain unchanged, even if the monster becomes Immune to Poison again.

-% Enemy Poison Resistance

-% Enemy Poison Resistance (EPR) reduces a target's poison resistance like LR, but only if PR < 100% i.e. not Immune to Poison. However, unlike LR -% EPR also applies to length, effectively applying Poison Length Reduced (PLR) by -%.

Monsters have no PLR % so -% EPR increases poison length by the displayed amount, although -100% is the absolute minimum to which a target can be reduced, doubling the length. The only exceptions are the Ancients, whose equipment can spawn with PLR % suffixes. Talic and Korlic can spawn with PLR >99%, which cannot be reduced by -% EPR. However, this doesn't result in effective immunity, since a frame of poison damage is still applied.

Players and hirelings are capped at PLR 75%, although the same difficulty penalties that apply to Resist % apply (-40% in Nightmare and -100% in Hell).

-% EPR is applied when the target is poisoned, like LR. Once poison has been applied its rate and length remain unchanged, so -% EPR can be removed afterwards without affecting damage or length.

25,022-26,317 bit rate for 350 frames results in 34,209-35,980 poison damage being applied over 14 seconds to a target with PR 0%. PR 110% makes a monster Immune to Poison, but casting level 10 LR (PR -11%) breaks that immunity and, combined with Trang-Oul's Wing Cantor Trophy's -25% EPR partial set bonus when equipping two other items from Trang-Oul's Avatar, results in the following:

Frames	= 350*(100-(0-25))/100
	= 350*1.25
	= 437

Min bit rate = 25,022*(100-(110-11-25))/100 = 25,022*0.26 = 6,505 Min damage = 6,505*437/256 = 11,104

Max bit rate = 26,317*(100-(110-11-25))/100 = 26,317*0.26 = 6,842 Max damage = 6,842*437/256 = 11,679

Thus 11,104-11,679 poison damage is applied over 17.48 (437/25) seconds. -% EPR can only be found on the following items:

Item	-% EPR
Rainbow Facet Jewel	3-5
Trang-Oul's Wing Cantor Trophy (3 Items)	25
Grief 'EthTirLoMalRal' Sword/Axe	20-25
Death's Web Unearthed Wand	40-50

Calculation

This is a summary of all the individual steps in the calculation of poison damage outlined in the preceding sections. To express total damage in points applied over a length in seconds:

Points = [Rate*Frames/256]

Second = Frames/25

Ideally damage is calculated measuring rate in bits and length in frames. It's also possible to calculate damage measuring rate in poison damage/second and length in seconds, which can be derived directly from displayed damage. However, the result will only be an approximation and rounding down should only be done at the end of the calculation for the maximum accuracy possible.

Rate = [([[B*S]*M]+[(I+[V*M])*M])*R]

[]	Round down
B	Skill rate
I	Sum of item rates
V	Venom rate
M	Mastery (+X% Poison Skill Damage)	M	= (100+X)/100
S	Synergy (+X% poison damage)	S	= (100+X)/100
R	Resistance	R	= (100-X)/100	If P >= 100 and P-(L/5) < 100 then X = P-(L/5) else R = 0 If P < 100 then X = Max(P-(L+E),-100) P Poison Resist X% P = X L Lower Resist (Poison Resist -X%) L = X E -X% Enemy Poison Resistance E = X

• If a single item has both a prefix and a suffix applying poison damage, then the rates and lengths of both are simply added.
• Gems, jewels and runes all count as separate items, even if they're socketed in a single item.
• Item and Venom rate are only added to the skill rates of Poison Dagger and the javelins (but not the clouds) of Poison and Plague Javelins.
• +% PSD isn't applied to item and Venom rate when applied by ranged attacks.

Frames = [F*R]

[]	Round down
F	Frames	Items Items + Skill Items + Venom Skill + Venom	F = sum of item lengths/number of items F = (skill length + sum of item lengths)/number of items F = Venom length F = skill length + Venom length
R	Resistance	R = (100-X)/100	If P < 100 then X = Max(P-E,-100) else F = 1 P Poison Length Reduced by X% P = X E -X% Enemy Poison Resistance E = X

• ERROR: Length is calculated differently when multiple items applying poison damage are used with skills that apply a fraction of weapon damage. Two items will apply poison damage over the sum of their lengths, while three or more items will just apply poison damage over the longest length of any of those items.