Penetration and Protection reduction Items

Hello, just a quick question that I could not find an answer to. I saw mention (I believe in the comments of someones god guide) that mentioned that items with Penetration and items that reduce physical Protection cancel each other out, or that you don't benefit from both? Is that right and if so does one completely negate the other? If so does the penetration negate the protection reduction or vice versa, or depends on purchase order? Or how does it work? Thanks

Penetration items work based on a hierarchy.

In case you aren't familiar with it yet, there's different types of penetration.

There's armor % reduction, Armor reduction, % armor penetration and flat armor penetration.

Examples:

• Armor % Reduction - The Executioner
• Armor reduction - Stone Cutting Sword
• % armor penetration - Titan's Bane
• Armor penetration - Jotunn's Wrath

I believe the hierarchy is in the exact same order as I've listed them, meaning:

Armor % reduction > Armor reduction > % Armor penetration > Armor penetration.

This means that an item with Armor % reduction, example The Executioner takes precedence over a % armor penetration item, example Titan's Bane.

In other, simpler words:

If an enemy has 100 armor, Titan's Bane would allow you to negate 33% of that, and The Executioner would take 36% of that after 3 hits.
However, due to the hierarchy, The Executioner will proc first, before Titan's Bane. This would mean that The Executioner will take 36% off of the enemy's armor, leaving, in this example case, only 64 armor left. (100 - 36% = 64, since any % of 100 is the % value)

That only leaves 64 armor for Titan's Bane to penetrate 33% of, making Titan's Bane less effective.


Hope this helped. The hierarchy may not be correct, I'm sure somebody else like Branmuffin17 will correct me if it is wrong.

The hierarchy is correct, so is the explanation.

This case of "efficiency reduction" can only apply to % penetration items, which are Titan's Bane and Obsidian Shard.
And it only occurs when they are combined with any protection reduction item.

However, it's worth noting that when they are combined with a flat protection reduction, like Void Shield, the efficiency reduction, while still present, is not THAT big of a deal
You are only "losing" about 7 protection shred, but the final result still gives you more penetration overall.


Example vs an opponent with 100 physical protection.

Titan's Bane alone
100 * (1 - 0.33) = 67
Final protections remaining : 67

Titan's Bane + Brawler's Beat Stick
100 * (1 - 0.33) = 67
67 - 20 = 47
Final protections remaining : 47

Titan's Bane + Void Shield
100 - 20 = 80
80 * (1 - 0.33) = 54 (53.6)
Final protections remaining : 54


As you can see, in that scenario, even if they both offer a kind of protection of 20, Void Shield reduced the efficiency of Titan's Bane, so the final protection is high than having Brawler's Beat Stick.
However, picking Void Shield should not be "banned" because of you already have Titan's Bane, because, as you can see, it is still better than having Titan's Bane alone.




Final note
While this calculation is exactly the same for magical protections (with Obsidian Shard and Void Stone), keep in mind that the majority of the mages only have 30 magical protection, without buying any defensive items.
Therefore, in that case, if you have both items, Obsidian Shard would only remove ... 3 protections.

Thank you for the replies and info, I learn a little more each day, thanks!

As above statements are correct, it's also important to note that some people that play Nemesis will do a 'Carry' build with attack speed and crit. I've done this myself and can say it can work if done right. However, what's important to note that Nemesis' ult, Divine Judgement STACKS with The Executioner, giving up to 86% protection reduction.

Yes, those calculation are valid no matter what the source of penetration or protection reduction is.
Abilities and items effects combine together to get the final stats.

Therefore, as Soren mentioned, Nemesis's Divine Judgement stacks with The Executioner.
Anhur's passive, Enfeeble and Guan Yu's Taolu Assault stack with Void Shield.
Anubis's passive, Sorrow, and Hel's Hinder stacks with Spear of the Magus.
Thanatos's Scent of Death, stacks with Brawler's Beat Stick.
Izanami's passive, Death Draws Nigh and Kali's passive Marked for Death stack with Titan's Bane, which means they get reduced efficiency if you have any protection reduction.

Also, don't forget that the flat penetration stat (the last one to be applied in the calculation) has a cap to 50.


Finally, there are 2 other stats, less frequent, that are applied after the protection calculation.
These are

% damage mitigation
- Shell
- Spirit Robe
- Osiris's Fragmented
- Cabrakan's Shadow Zone
- Khepri's Rising Dawn

flat damage mitigation
- Mark of the Vanguard