Poison Damage

Poison Damage is a Pandora's Box of mystery that few people dare to open, in Diablo 2. The nuances and intricacies of this unique mechanic can leave many scratching their heads in confusion. In this article, we break down how Poison Damage is calculated, how different sources interact with one another, how Skills react when combined and everything else you need to know to fully maximize your Poison game.

Poison Damage

Poison Damage applies Poison Length. This Length applies the calculated Poison Bit Rate from all sources, over a calculated amount of time.

• Poison Damage is applied as Poison Bit Rate per Frame, over the total Poison Length. To understand Bit Rate and calculating Poison Length, see Bit Rate Conversion, below.
• While Poisoned, the target shows with a bright green color.
  • If Cold Length or holyfreeze Slow is applied to the same target, then they shows as blue instead of green.
• Poison Length applies damage per frame, which stops Monster Damage Regeneration.
• Poison Damage is only applied in a Frame, if no other source of damage is applied in that same Frame.
  • Open Wounds causing damage in a Frame, allows Poison Damage to also apply in that frame. This is the only exception.
• Once a target is Poisoned, incoming attacks / Skills that would apply Poison Damage have 1 of 3 outcomes:
  1. The incoming source has a larger or equal Poison Bit Rate, delivered by a Character, Mercenary, or Summon:
     • The incoming attack deals its Bit Rate damage instead of the current Bit Rate and then replaces the current Poison Length, with the new Poison Length.
  2. The incoming source has a smaller Poison Bit Rate, delivered by a Character, Mercenary, or Summon:
     • The incoming attack deals its Bit Rate damage instead of the current Bit Rate and fails to replace the existing Poison Length.
  3. The incoming source has a Poison Bit Rate, delivered by a monster:
     • The incoming attack deals its Bit Rate damage in addition to the current Bit Rate and then replaces the current Poison Length, if its Bit Rate is higher. If it is lower, the existing Poison Length continues.
• If a Character is using whirlwind with two 1-Handed Weapons that each apply Poison Damage, then both sources apply their Bit Rate damage for the first Frame, and then the highest Bit Rate applies its Poison Length. For subsequent attacks, it follows the above logic.
• Poison Length Damage can only reduce a Character to 1 remaining Life.
  • Incoming attacks that would apply Bit Rate can kill a Character.
  • Monsters, Summons, and Mercenaries can die due to Poison Length Damage.

Poison Bit Rate Conversion

To understand Poison Damage and how the game calculates it, we need to first understand the terms Bit, Frame, and Bit Rate. We use Toxic Small Charm as our example.

Bit

The game converts Poison Damage into Bits. A Bit is a unit of Damage measurement for sources that deal Damage over Time (DoT). Each 1 point of Damage is 256 Bits.

• Bits are the smallest unit of measurement for Damage.
• The game does not round Damage properly when converting back up to points, from Bits. Any calculation of Bit Damage in terms of points and seconds is inaccurate, due to rounding errors.
• Bits are used to determine a source of Poison's Bit Rate, which relies on its Frame count.

Frame

A Frame is the smallest unit of measurement for the game's engine, in time. 1 Frame is 1/25^th of a second.

• 1 Second = 25 Frames.
• While Frames are normally used to describe the lengths of an animation, the entire game actually runs off Frame Length.
• Bit Rate damage is applied every Frame.

Bit Rate

Bit Rate is the Bit Damage of a Poison source, divided by the number of Frames indicated on the source of Poison Damage.

• A Toxic Small Charm says "100 Poison Damage over 5 Seconds". We need to determine this source's Bit Rate.

Bit Rate = [(Poison Damage * 256 Bits) / (Seconds * 25 Frames)]
Bit Rate = [(100 * 256) / (5 * 25)]
Bit Rate = 205 Bits per Frame

• We communicate the Poison Length as Frames, with respect to seconds.

Poison Length = (Frames) / 25
Frames = Poison Length in Seconds * 25
Poison Length = 125 / 25

• While this simplifies to 5 seconds, we need to use the Poison Length in Frames for future calculations.
• We have 205 Bit Rate over 125 / 25 Frames. This single source of Poison Damage would deal 205 Bit Rate damage, every Frame, for a total of 125 Frames OR 0.8 Damage every 1/25^th of a second for 5 seconds.

Poison Bit Rate / Poison Length Calculation

When an attack carries multiple sources of Poison Bit Rate and Length, the game combines these values differently, depending on the sources.

• Charms with Poison Affix AND Suffix: Toxic Small Charm of Anthrax
  • The two values of Poison Damage are converted to Bit Rate, then added together, and the total Poison Length is summed.
    • The item displays the Bit Rate calculated as Poison Damage over Seconds, but due to rounding errors, this is typically slightly higher than the actual value.

When multiple items apply Poison Bit Rate, their Rates are added, and the Lengths are averaged.

• Jewels (Jewel of Envy) and perfectemeralds socketed into items, count as separate item sources for this calculation.

• The Frames (Length) the summed Bit Rate would apply over is 704 / 3 = 234 Frames.
  • This Damage, in Points over Seconds would be 853 Poison Damage over 9.36 Seconds.

The Poison Length is calculated differently for multiple sources of Poison Damage that are applied by a Skill which applies less than 100% of a Weapon's Damage.

• For multipleshot our Length from the above example would apply:
  • [704 / (3 - 1)] = 352 Frames
  • This Damage, in Points over Seconds would be 1284 Poison Damage over 14.08 Seconds.
• For bladesentinel our Length from the above example would apply:
  • Sum of Lengths = 704 Frames
  • This Damage, in Points over Seconds would be 2568 Poison Damage over 28.16 Seconds.

Poison Damage Skills

There are 8 Poison Damage Skills in Diablo 2.

plaguejavelin

• Throws a Javelin that spreads a ~6 yard cloud that applies Poison Damage within its area.
• The Javelin itself also applies Poison Damage from item sources.
  • While the Skill's Damage on Javelin is increased by +xx% Poison Skill Damage, the Item Poison Damage is not increased by this Stat.
• The Minimum and Maximum Poison Bit Rates increase with Skill Level.
• The Poison Length increases with Skill Level.

poisoncreeper

• A Summon, that applies Poison Damage in a Size 3 area (An Urdar's Body) when it attacks.
• The Minimum and Maximum Poison Bit Rates increase with Skill Level.
• The Poison Length is set to 100 Frames.
• The Bit Rate Damage applied by

poisondagger

• Makes an Attack with an equipped Dagger that applies Poison Damage.
• The Minimum and Maximum Poison Bit Rates increase with Skill Level.
• The Poison Length increases with Skill Level.
• Any Poison sources from Items, have their Bit Rate added to the Skill Bit Rate.
  • Their Lengths are added to the Skill's then it's divided by the number of items.

poisonexplosion

• Explodes a targeted corpse to spread a 2 yard cloud that applies Poison Damage within its area.
• The Minimum and Maximum Poison Bit Rates increase with Skill Level.
• The Poison Length increases with Skill Level.

poisonjavelin

• Throws a Javelin that spreads a ~2 yard cloud that applies Poison Damage within its area.
• The Javelin itself also applies Poison Damage from item sources.
  • While the Skill's Damage on Javelin is increased by +xx% Poison Skill Damage, the Item Poison Damage is not increased by this Stat.
• The Minimum and Maximum Poison Bit Rates increases with Skill Level.
• The Poison Length increases with Skill Level.

poisonnova

• Releases missiles in a 360^o radius, applying Poison Bit Rate to all targets that are hit.
• The Minimum and Maximum Poison Bit Rates increases with Skill Level.
• The Poison Length is set to 50 Frames.

rabies

• Applies Poison Bit Rate upon successfully attacking with the Skill.
  • The Skill applies an Infection Length that spreads to other targets within range. See the Druid Overview here for in-depth Skill mechanics.
• The Minimum and Maximum Poison Bit Rates increases with Skill Level.
• The Poison Length increases with Skill Level.

venom

• Adds a Poison Bit Rate to Weapon attacks and attack Skills for the duration.
• Truncates all Poison Damage source's Lengths to 10 Frames (0.4 Seconds).
  • This applies their total Bit Rates over a much shorter Length, drastically increasing their damage.
• Venom's Bit Rate and Length are added to the lengths of poisondagger, poisonjavelin and plaguejavelin Javelins. (Not their clouds)
• +xx% Poison Skill Damage is applied when cast and also when the Bit Rate is applied by attacks / Skills.

Bit Rate with Skills

Skills which apply Poison Bit Rate via an attack, also applies Poison Damage from item sources. This often leads to lower Poison Damage being applied per second because of how Poison Length is calculated. The Skill venom opens a lot of doors to increase Poison Damage.

The D2Planner below shows a poisondagger Necromancer setup, along with it's fully Synergized Skill Tree. We'll use this example to show the changes in Poison Length calculations. After, we apply venom via the Chance to Cast proc from treachery.

Level 30 poisondagger with full synergies from poisonexplosion and poisonnova applies 12,383 to 12,909 Poison Damage over 13.6 Seconds. This is 9,234 to 9,720 Bit Rate over 340 Frames. Let's see how this Skill interacts with the other sources of Poison Damage we have equipped.

• Since this is a Skill with Item sources of Poison Damage, the Length is the summed total, divided by the number of items.
  • 1,044 / 3 = 348 Frames
  • This makes our Minimum Bit Rate 10,258 and our Maximum Bit Rate 10,654.
    • 13,944 to 14,482 Poison Damage over 13.92 Seconds.

• Because venom truncates the Item sources of Bit Rate, their summed total is added, and their Lengths are replaced with venom's, leaving us with 350 total Length.
• Poison Length = 350 Frames = 14 Seconds
• Our Minimum Bit Rate is 18,066 and our Maximum Bit Rate is 18,974.
  • 24,699 to 25,941 Poison Damage over 14 Seconds.

+xx% Poison Skill Damage

Applies a percentage increase to Skill Damage for each Poison Damage Skill, differently. In addition to Skills, this adds a percentage increase to Poison Damage from items for melee and ranged Attacks.

• The increase in Damage is applied to the Bit Rate, the Length is not affected by this increase.
  • This is multiplicative, with any Synergy bonuses.
• venom's Damage is increased when cast, and also increased when applied to an attack.
• poisoncreeper does not benefit from this Stat.

Resistances

Resistances affect the Bit Rate when the source of Poison Damage is applied to the target.

• 1% of Poison Resistance decreases incoming Poison Bit Rate by 1%
• Having 100% Poison Resistance makes monsters Immune to Poison Damage. No Poison Length is applied to a monster that is Immune.
  • Lowering a target's Resistance after Bit Rate is applied does not affect the current Bit Rate, since it checks the target's Resistance at the point of application.
• lowerresist reduces a target's Poison Resistance, reducing the amount of damage mitigated by the target's Poison Resistance.
  • lowerresist does not impact Poison Length in any way.

Poison Length Reduced (PLR)

This Stat, which only Characters, Mercenaries, and Units which wear Items have access to, reduces Length of Poison applications.

• Poison Length Reduced has a minimum value of -100%, and no maximum.
  • PLR of >99% causes the first Frame of Poison Bit Rate to apply to the attack, but no Poison Length is applied.
  • -100% PLR doubles the Length of any applied Poisons. This doubles the total damage dealt, if the entire Length runs its course.
  • Characters and Mercenaries have a cap of 75% PLR.
  • Difficulty penalties for PLR:
    • -40% in Nightmare
    • -100% in Hell
• PLR is checked during Poison Length application, and is not affected by changing its value during the Length.
• PLR is reduced by -xx% Enemy Poison Resistance.
  • Example: A Unit with 75% PLR, targeted by a source with -50% Enemy Poison Resistance, has an effective PLR of 25%.
• cleansing Aura has a unique PLR function. It applies its value of PLR, every 2 seconds, without any Difficulty penalties or cap.
• Percentage % PLR = min(30 + [60 * [ (110*slvl) / (slvl+6) ] / 100] , 90)
  • Skill Level 1 = 39% PLR
• If we have a Poison Length of 50 seconds, after equipped PLR, and our cleansing Aura begins reducing 2 seconds into this Length, the reductions would be:
  • 48 seconds * (1 - .39 PLR) = 29.28 seconds remaining
  • 27.28 seconds * (1 - .39 PLR) = 16.64 seconds remaining
  • 14.64 seconds * (1 - .39 PLR) = 8.93 seconds remaining
  • 6.93 seconds * (1 - .39 PLR) = 4.227 seconds remaining
  • 2.227 seconds * (1 - .39 PLR) = 1.358 seconds remaining
  • So the 50-second Poison Length, only lasts for 11.358 seconds with Level 1 cleansing Aura active.

-xx% Enemy Poison Resistance (EPR)

This Stat reduces a target's Poison Resistance, and their Poison Length Reduced by %.

• Only applies to targets who are not considered Immune (>100% Poison Resistance).
• There is a minimum cap of -100% Poison Resistance, which effectively doubles incoming Bit Rate Damage.
• The reduction to Poison Length Reduced by % works the same as Poison Resistance. Every -1% EPR decreases the Length Reduction of PLR by 1%.
  • Reducing a target to -100% PLR doubles the effective Poison Length applied by a source.
• -xx% EPR is checked at the point of Bit Rate and Poison Length application. Changing the total EPR afterwards does not affect the current Poison Length or Bit Rate.

Summary

• Poison Damage is measured in Bit Rate and Poison Length (in Frames). The values you see on items and the Character Screen are largely inaccurate.
• Poison Damage from multiple sources can drastically change the Poison Length, which lowers Damage Per Second but increases overall damage.
• venom truncates Poison Damage from items into a single source, and changes how multiple sources apply to other Skills. Finding a way to cast venom drastically increases your total damage, while making calculations easier.
• +xx% Poison Skill Damage increases your Bit Rate, target Resistances reduces Bit Rate, and -xx% Enemy Poison Resistance increases Bit Rate and Poison Length.
• Each Poison Damage Skill acts very differently from the others. Check out each one's mechanics to better understand these nuances.

And there you have it! Poison Damage calculations, and explanations at your fingertips. Now go out there and shout to the world! "I know how Poison Damage works in Diablo 2!"

Credits

Written by MacroBioBoi
Reviewed by Teo1904