Question on penetration/shred

I have a few dumb questions and the most relevant older threads I could find are from 2019.

What is the difference between penetration and shred, be it armor or resistance? I think I know but I won’t embarrass myself.

I know penetration really only comes on amulets for the most part (not including idols, uniques etc) so when is it beneficial to take penetration over % damage or crit multiplier?

I generally want to take crit multi on amulet but it’s also because I’m not certain how much more beneficial penetration is. I know it’s supposed to bypass X resistance because I’ve read the resistance tooltip but not sure how effective this really is. That being said I know most build guides have penetration in the amulet slot so I assume its worth more than whatever crit multi, % damage etc you can put there but I don’t know the math.

Are there any scenarios in which it’s better to skip penetration?


Penetration does exactly what you are probably thinking about, it bypasses a given amount of % resistances of the enemy. This even can go into the negative, so even on enemies with 0 resistance (which most enemies have) it will increase your damage.


  • You have 9% Physical Penetration on your Amulet
  • A enemy has 30% physical resistance

If you damage that enemy, his resistance will get calculated as if it has 21% physical resistance (you penetrate 9% of his physical resistance).

If the enemy has less than 9% physical resistance you will penetrate further than 0, so his resistance get’s calculated as negative, which increases your damge further.

Example with specific numbers

You use a skill that does 100 damage (every damage colaculation from player side already included) and you hit an enemy with and without penetration.
(Enemy has 30% resistance)

Without Penetration: 100 * (1,00 - 0,30) = 70 damage inflicted

With Penetration: 100 * (1,00 - 0,21) = 79 damage inflicted

In this example you deal ~12,85 more damage with the penetration.

To say if it’s better than %damage or crit multi is really hard to answer, generally and really depends on alot of things.
But usually on alot of well established endgame builds it’s probably one of the best stats, since it basically acts as some sort of “more multiplier”, since it elevates your whole damage output.

I would say in the majority of cases % increased X damage is worth less than crit multi and penetration, at least on builds that already have alot of %increased damage from other sources (such as other gear pieces, passives or idols).

Crit Multi can be really good to, but it also heavily depends on the build, how much crit multi is worth.

As a rule of thumb i would say both Crit Multi and Penetration are the best offensive stat. Crit Multi obviously only apply to crit builds, while penetration will work for everything, including ailments and DoT builds.

If you are doing a build that has several damage types penetration is definitely the weakest offensive stat, since more generic stats like “spell damage” or “damage over time” are better since they boost all damage types.


Shred basically function the same way, but as a temporary debuff on the enemy, which also has a stack limit of 20 stacks.
Shred also reduces the enemies resistance on a given type.

Shred does shred 5% resistance shred per stack with a stack limit of 20 stacks.

On bosses and player shred does only shred 2% per stack with the same stack limit of 20.

Also Penetration and shred do work together.

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They both do the same thing, reduce resists so the target takes more damage.

Penetration only applies to the damage from the skill that has it (if you can get penetration from a passive node, such as the Acolyte then it would apply to all of the player’s damage).

Shred has a max number of stacks (20, excluding the poison shred that the poison ailment has by default) & a duration so any damage (of the appropriate element) the target takes will be affected by it.

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I disagree. Whether it’s more effective to get penetration or not depends on the total of your increased damage. Since penetration is only available (as an affix) on amulets, at (max roll) t5 it competes with a 70% increased damage affix so for the penetration affix to be more effective than the increased damage affix you’d need to have more than 777% increased damage (in total). If the penetration is coming from a skill, it’s competing with other “more” modifiers & then it’s an easy comparison, just pick which has the biggest number. If the penetration is coming from a passive node than it’s fairly easy & the penetration is likely the best choice (since you have so many passive points).


Both of these helped a lot, thank you guys, I really appreciate it!

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