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League of Legends | What Is Lethality and How Does It Work?

Even though it was introduced back in 2017, I only recently began to fully understand Lethality. In short, it’s a boost to armor penetration. But it’s also more complicated than that. League of Legends Lethality is not a “simple” stat — it’s a singular part of a messy formula that results in armor penetration.

Would it be simpler if Riot just returned the old armor penetration stat? Definitely. But this doesn’t seem like it’s happening anytime soon. So for now, we’re stuck with trying to work out a mathematical equation to figure out our actual armor penetration.

In this article, I’ll explain how the Lethality formula works, what its downsides are, and which Champions you should be building it on. 

Lethality 101: League of Legends Lethality Explained

You’ve heard the term thrown around here and there. But in LoL, what is Lethality, exactly? Let’s break it down.

According to the League of Legends wiki, the formula for armor penetration is as follows:

Flat Armor Penetration = Lethality x (0.6 + 0.4xlevel ÷ 18)

What this means, essentially, is that flat armor penetration is a direct result of your Lethality and level. Lethality will be worth less in the early game, but by the time you reach Level 18, you will be receiving the full benefit. 

Another aspect you need to understand is that flat armor penetration is not the only stat that affects a target’s armor. There is also flat armor reduction, percentage armor reduction, and percentage armor penetration. These stats all affect a target’s armor in the following order:

  1. Flat Armor Reduction
  2. Percentage Armor Reduction
  3. Percentage Armor Penetration
  4. Flat Armor Penetration (Lethality)

Let’s check out a brief description of each of these additional stats.

Lethality 2
Image: Riot Games

Flat Armor Reduction

This is the easiest to understand. If a target’s armor is affected by a flat reduction, the deduction will be directly removed from their armor. 

For example, if a target has 200 total armor and is affected by 80 armor reduction, their new total armor will be 120. This deduction is distributed between their base and bonus armor. Flat Armor Reduction can also reduce a target’s total armor to a negative number. This is most effective against Champions with little to no bonus armor.

Percentage Armor Reduction

Percentage armor reduction works by multiplying a target’s armor by (100% – the amount of percent armor reduction). If a flat armor reduction occurs in addition to percent armor reduction, this equation uses the total armor after the flat reduction.

For example, if a target has 100 base armor and 100 bonus armor and is affected by 30% armor reduction, the equation looks like this:

(100 base armor x 0.7) + (100 bonus armor x 0.7) = 140 total armor

Therefore, a target with 200 total armor and a 30% armor reduction will effectively have 140 total armor after the deduction.

Percentage Armor Penetration

Percentage Armor Penetration does not change a target’s armor value. It only matters when calculating damage, as it causes their armor to be treated as if it were lower than it actually is. In the equation, a target’s base and bonus armor is multiplied by (100% ˗ amount of armor penetration)

For example, if a target has 50 base armor and 150 bonus armor and is affected by 20% armor penetration, the equation is as follows:

(50 base armor x 0.8) + (150 bonus armor x 0.8) = 160 total armor 

However, this equation is only used to calculate damage. Percent armor penetration doesn’t actually change the target’s armor value, so any other effects that are based on the target’s total armor won’t be affected by percent armor penetration.

Breaking It All Down

kayn math - breaking it all down
Image: Riot Games via HGG

I know this has been confusing, but bear with me — we’re almost done. Like I said before, each type of armor reduction or penetration is applied in a specific order: Flat Armor Reduction, Percent Armor Reduction, Percent Armor Penetration, Lethality. For Lethality calculation, we will assume the champion doing the damage is Level 16.

For this example, we’ll consider a target that has 50 base armor and 150 bonus armor. They are affected by 15 flat armor reduction, 20% armor reduction, 15% armor penetration, and 50 Lethality. 

Flat Armor Reduction: Reduces to 185 total armor. 46.25 base and 138.75 bonus.

(50 base armor – 3.75) + (150 bonus armor – 11.25) = 185 total armor

Percent Armor Reduction: Reduces to 148 total armor. 37 base and 111 bonus.

(46.25 base armor x 0.8) + 138.75 bonus armor x 0.8) = 148 total armor

Percent Armor Penetration: For damage calculation purposes, reduces to 125.8 total armor. 31.45 base and 94.35 bonus.

(37 base armor x 0.85) + (111 bonus armor x 0.85) = 125.8 total armor

Lethality (Flat Armor Penetration): Reduces target’s armor total to 78.1. However, just like Percent Armor Penetration, this does not technically reduce the target’s armor total. It is for damage calculation purposes only.

50 Lethality x (0.6 + 0.4 x 16 ÷ 18) = 47.7

The end result?

125.8 total armor – 47.7 Lethality =  78.1 total armor

Yeah, it’s pretty ridiculous.

How to Optimize Your Lethality

If you’re playing a Champion that wants Lethality, there are several ways to optimize it. The best way is to combine it with armor reduction. Combining Lethality with armor reduction allows you to cut through even more armor, which is the best end result. You can also just not worry about armor reduction and go for a ton of Lethality, but there’s really no need. The best method is to combine your League of Legends Lethality stat with other stats, including Attack Damage. Here are some items I highly recommend.

Lethality Items

Here are some of the top League of Legends Lethality items to add to your kit.

Duskblade of Draktharr (Mythic)

Duskblade of Draktharr (Mythic)

Duskblade is one of the classic Lethality items, and remains strong even after the items rework. It offers 75 Attack Damage, 26 Lethality, and 25 Ability Haste. It has an ability called Nightstalker that causes your first attack against an enemy to do extra damage, slows them by 99%, and makes you invisible if they die within three seconds of your attack. Its mythic passive grants your legendary items 5 Ability Haste, so it’s good for Champions that care about that more than just damage and Lethality. 

Syzygy (Mythic)

Syzygy (Mythic)

This item is only available if Ornn is on your team. Syzygy gives 75 Attack damage, 26 Lethality, and 10% Omnivamp. It has an ability called Ever Rising Moon, which activates if you hit two abilities or attacks within 1.5 seconds. Ever Rising Moon does percent health damage, gives you bonus movement speed for a short time, and gives you a temporary shield. Syzygy’s mythic passive gives your legendary items 4% armor penetration. This is my favorite mythic item for assassins if it’s available. 

Prowler’s Claw (Mythic)

Prowler’s Claw (Mythic)

Prowler’s Claw gives 60 Attack Damage, 21 Lethality, and 20 Ability Haste. It’s ability is called Sandswipe, which is an active that allows you to dash through an enemy and deal physical damage to them. You also do additional damage to that enemy for a short time after this occurs. Its mythic passive grants legendary items 5 Lethality. If you’re focused on just Lethality, this is definitely the best mythic for you.

Youmuu’s Ghostblade

Youmuu’s Ghostblade

Youmuu’s gives you 60 Attack Damage and 18 Lethality. Its active is called Wraith Step, and gives you 20% bonus movement speed upon activation and 40 flat movement speed out of combat. This is probably the best non-mythic Lethality item in the game, especially for champions that also want high movement speed. 

Edge of Night

Edge of Night

Edge gives 50 Attack Damage, 10 Lethality, and 325 Health. Its active, Annul, grants a spell shield that blocks the next enemy attack. I personally like Edge of Night most on brawlers because of the bonus health, but it’s a fine pick for any Lethality user. The only real downside to Edge of Night is that it can be difficult timing the spell shield correctly. But, that’s just something you have to get a feel for. 

Other Important Items for Lethality

Here are some less crucial (but still hugely beneficial) items for Lethality!

Black Cleaver

Black Cleaver

Black Cleaver is the only item on this list that I consider essential for Lethality users. It offers 40 Attack Damage, 400 Health, and 25 Ability Haste. What makes it so good is its ability — dealing damage with Black Cleaver gives its target a stack of 5% armor reduction, up to a max of 30% reduction. Since this is one of the only ways to apply armor reduction in the game, there’s no reason not to use this item with the Lethality ones. 

Serylda’s Grudge

Serylda’s Grudge

This item gives 45 Attack Damage, 30% Armor Penetration, and 20 Ability Haste. It also has an ability that allows you to slow enemies, but that’s not why it’s so good. Having percent armor penetration is excellent alongside Lethality, especially against Champions with very high armor. This is one of the stronger items for Lethality brawlers, but can be used on almost any Lethality user.

Lord Dominik’s Regards

Lord Dominik’s Regards

Lord Dominik’s Regards gives 30 Attack Damage, 20% Critical Strike Chance, and 35% Armor Penetration. This item is commonly played on marksmen that need a way to deal with super tanks, but it also works on brawlers in the Lethality realm. While not an essential item, it combines well with Lethality items or standard ADC builds that prioritize critical strike chance. Since this is one of the only armor penetration items that includes critical strike chance, I highly recommend it on any ADC.

Divine Surrender (Mythic)

Divine Surrender (Mythic)

Divine gives 40 Attack Damage, 400 Health, and 20 Ability Haste. Its mythic passive gives all legendary items 5% armor penetration and 5% magic penetration. This hybrid penetration type makes the item strange overall. It’s very good on Lethality users that can benefit from this hybrid nature, but might feel strange on more straight forward attack damage users. 

Kraken Slayer (Mythic)

Kraken Slayer (Mythic)

Kraken Slayer gives 65 Attack Damage, 25% Attack Speed, and 20% Critical Strike Chance. Its ability makes every third attack do bonus true damage, so its a staple for marksmen. While this item isn’t commonly used on Lethality builds, I think it has potential. If you’re playing a marksman and want something that goes reasonably well with some Lethality (but not a ton), then this might be a great choice for you. Be careful if you do choose to use this item, though. It doesn’t directly combo with Lethality, so you’ll need to lay out the rest of your build to work with it. 

Lethality Downsides

There aren’t many downsides to the League of Legends Lethality stat. That being said, there are a few things worth mentioning in regards to how it can become bad.

For one, you have to be careful about how you build it. If you end up with too much Lethality and not enough damage, then you won’t be able to benefit from the armor reduction. If you end up with lots of damage but not enough Lethality, the opposite occurs.

When building Lethality, you have to make sure you have a good balance of other stats as well. This is not a one-trick kind of stat. Think of it more as a supporting one.


Become a High Grounder

League of Legends Lethality and the other armor-affecting stats can be difficult to understand. There’s far more math involved than anyone wants to deal with, but just understanding how it works is good enough to be able to use it. Don’t get frustrated with trying to calculate exactly how your stats affect Lethality, because there’s no need to understand it all. Make sure and enjoy the game for what it is and not to hate it for what it isn’t. 

In the meantime, subscribe to our newsletter for awesome guides straight to your inbox. Happy gaming!

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