Armor Pen vs. Lethality in LoL: Which One to Build

Armor penetration and lethality both cut through enemy armor, but they punish different targets. Percent armor penetration ( Serylda's Grudge Serylda's Grudge 3,000 gold 45 Attack Damage 35% Armor Penetration 15 Ability Haste Bitter Cold Damaging Abilities Slow enemies below 50% Health by 30% for 1 second. , Mortal Reminder Mortal Reminder 3,000 gold 35 Attack Damage 30% Armor Penetration 25% Critical Strike Chance Grievous Wounds Dealing physical damage applies 40% Wounds to enemy champions for 3 seconds. ) removes a share of the target’s total armor, so it scales up against tanks who have stacked a lot of it. Lethality ( Youmuu's Ghostblade Youmuu's Ghostblade 2,800 gold 55 Attack Damage 18 Lethality 4% Move Speed Haunt Gain Move Speed while out of combat. Wraith Step Gain Move Speed and Ghosting for seconds. , The Collector The Collector 3,000 gold 50 Attack Damage 10 Lethality 25% Critical Strike Chance Death Your damage executes champions that are below 5% Health. Taxes Champion kills grant 25 bonus gold. ) is flat penetration, so it hits hardest against squishy targets with little armor to begin with and loses value the tankier the target gets.

What Armor Penetration and Lethality Actually Do

Both stats reduce the armor your damage calculates against, but they work on different parts of the formula. Percent armor penetration (the stat on items like Last Whisper and Serylda’s Grudge) removes a percentage of the target’s armor before damage is calculated: against a squishy target with 40 armor it barely matters, against a frontliner with 200+ armor it removes a large chunk of their effective resistance.

Lethality is flat armor penetration dressed up under a different name. It subtracts a fixed number from the target’s armor, so it does the same amount of work whether the target has 40 armor or 400. Against a low-armor target that fixed number can erase most or all of their armor; against a stacked tank it barely dents the total.

The League of Legends Wiki lists the official reduction order as four steps: flat armor reduction, percent armor reduction, percent armor penetration, then flat armor penetration last. That means your percent pen items ( Serylda's Grudge Serylda's Grudge 3,000 gold 45 Attack Damage 35% Armor Penetration 15 Ability Haste Bitter Cold Damaging Abilities Slow enemies below 50% Health by 30% for 1 second. , Last Whisper Last Whisper 1,450 gold 20 Attack Damage 18% Armor Penetration ) calculate first, shrinking the target’s armor, and your lethality ( Youmuu's Ghostblade Youmuu's Ghostblade 2,800 gold 55 Attack Damage 18 Lethality 4% Move Speed Haunt Gain Move Speed while out of combat. Wraith Step Gain Move Speed and Ghosting for seconds. , The Collector The Collector 3,000 gold 50 Attack Damage 10 Lethality 25% Critical Strike Chance Death Your damage executes champions that are below 5% Health. Taxes Champion kills grant 25 bonus gold. ) then subtracts its flat amount from whatever is left. Running both at once is not redundant: the percent pen reduces the pool before the flat pen takes its fixed bite out of it.

One mechanic change matters for anyone still going off old guides: lethality used to scale down at early levels, granting only a fraction of its stated value before level 18. Since the Season 14 item rework, lethality applies its full flat value at every level, including level 1. A 18-lethality Youmuu's Ghostblade Youmuu's Ghostblade 2,800 gold 55 Attack Damage 18 Lethality 4% Move Speed Haunt Gain Move Speed while out of combat. Wraith Step Gain Move Speed and Ghosting for seconds. removes 18 armor whether it’s minute 5 or minute 35.

The Crossover Point: Where Each One Wins

Run the same two numbers against a squishy target and a tank to see why the item choice flips. Take Serylda's Grudge Serylda's Grudge 3,000 gold 45 Attack Damage 35% Armor Penetration 15 Ability Haste Bitter Cold Damaging Abilities Slow enemies below 50% Health by 30% for 1 second. at 35% armor penetration against two different targets: a mage with 60 armor loses 21 armor to that percentage, while a frontline bruiser with 220 armor loses 77. The percentage scales with whatever armor is already there, so it keeps paying off the more armor the target stacks.

Now run 18 flat lethality ( Youmuu's Ghostblade Youmuu's Ghostblade 2,800 gold 55 Attack Damage 18 Lethality 4% Move Speed Haunt Gain Move Speed while out of combat. Wraith Step Gain Move Speed and Ghosting for seconds. ) against the same two targets: the mage loses the same 18 armor they would at any armor total, which against their 60 armor is a huge relative cut, while against the bruiser’s 220 armor those 18 points barely move the needle.

The two trade places somewhere around 100 to 150 armor, depending on exactly how much penetration you’re running. Below that range lethality does more relative work per gold spent; above it, percent penetration pulls ahead. That’s why assassins and marksmen who expect to be hitting squishy backline targets lean lethality, while duelists and skirmishers who spend most fights trading with the enemy frontline lean percent penetration, even though both are nominally “armor pen” items.

Which Items to Build: Lethality vs. Percent Armor Pen

Lethality items, for champions diving squishy backline targets: Youmuu's Ghostblade Youmuu's Ghostblade 2,800 gold 55 Attack Damage 18 Lethality 4% Move Speed Haunt Gain Move Speed while out of combat. Wraith Step Gain Move Speed and Ghosting for seconds. (55 AD, 18 Lethality, plus a move speed burst to close the gap), The Collector The Collector 3,000 gold 50 Attack Damage 10 Lethality 25% Critical Strike Chance Death Your damage executes champions that are below 5% Health. Taxes Champion kills grant 25 bonus gold. (50 AD, 10 Lethality, 25% crit, executes below 5% HP), and Edge of Night Edge of Night 3,000 gold 50 Attack Damage 15 Lethality 250 Health Annul Grants a Spell Shield that blocks the next enemy Ability. (50 AD, 15 Lethality, 250 Health, a spell shield that keeps a squishy assassin alive long enough to use the rest of the build). The Brutalizer The Brutalizer 1,337 gold 25 Attack Damage 10 Ability Haste 5 Lethality is the early lethality component most AD assassins and some junglers rush for the 25 AD and 10 ability haste alone.

Percent armor penetration items, for champions expecting to fight through a frontline: Serylda's Grudge Serylda's Grudge 3,000 gold 45 Attack Damage 35% Armor Penetration 15 Ability Haste Bitter Cold Damaging Abilities Slow enemies below 50% Health by 30% for 1 second. (45 AD, 35% armor pen, 15 ability haste, slows below 50% HP), Mortal Reminder Mortal Reminder 3,000 gold 35 Attack Damage 30% Armor Penetration 25% Critical Strike Chance Grievous Wounds Dealing physical damage applies 40% Wounds to enemy champions for 3 seconds. (35 AD, 30% armor pen, 25% crit, plus Grievous Wounds against sustain tanks), and Lord Dominik's Regards Lord Dominik's Regards 3,300 gold 35 Attack Damage 35% Armor Penetration 25% Critical Strike Chance Giant Slayer Deal up to 15% bonus damage against champions based on their bonus Health. Maximum damage bonus reached at 1500 bonus Health. (35 AD, 35% armor pen, 25% crit, bonus damage scaling with the target’s bonus health, a dedicated tank-shredder for marksmen). Last Whisper Last Whisper 1,450 gold 20 Attack Damage 18% Armor Penetration is the cheap 18% armor pen component (1450g) that most AD champions pick up as a second or third item regardless of matchup.

The Black Cleaver The Black Cleaver 3,000 gold 200 Health 50 Attack Damage 10% Cooldown Reduction Wicked Edge: 10 Lethality Cleaving Strike: Dealing physical damage to an enemy champion reduces their Armor by 5% for 4 seconds (stacks up to 5 times, up to 25%). sits in its own category: it gives 10 flat lethality through its passive, but its Cleaving Strike effect stacks a separate 5% armor reduction per hit (up to 25% at 5 stacks) directly onto the target, independent of your own penetration stats. That reduction benefits your whole team, which is why bruisers and juggernauts who expect extended fights build it even against armor-stacking comps where pure lethality would otherwise be the wrong call.

Decision Table: Target Type to Penetration Type

Use this as a starting reference, then check the actual armor totals in your game: the same way aggregate item win rates can mislead you, a generic table cannot see what the enemy team actually built.

What you’re facing	Build this	Why
Squishy backline ( Ahri Ahri the Nine-Tailed Fox , Jinx Jinx the Loose Cannon , any carry under ~70 armor)	Lethality ( Youmuu's Ghostblade Youmuu's Ghostblade 2,800 gold 55 Attack Damage 18 Lethality 4% Move Speed Haunt Gain Move Speed while out of combat. Wraith Step Gain Move Speed and Ghosting for seconds. , The Collector The Collector 3,000 gold 50 Attack Damage 10 Lethality 25% Critical Strike Chance Death Your damage executes champions that are below 5% Health. Taxes Champion kills grant 25 bonus gold. )	Flat pen erases most of their armor in one hit; percent pen has little armor to work with
Stacked tank ( Ornn Ornn The Fire below the Mountain , Maokai Maokai the Twisted Treant , 200+ armor)	Percent pen ( Serylda's Grudge Serylda's Grudge 3,000 gold 45 Attack Damage 35% Armor Penetration 15 Ability Haste Bitter Cold Damaging Abilities Slow enemies below 50% Health by 30% for 1 second. , Lord Dominik's Regards Lord Dominik's Regards 3,300 gold 35 Attack Damage 35% Armor Penetration 25% Critical Strike Chance Giant Slayer Deal up to 15% bonus damage against champions based on their bonus Health. Maximum damage bonus reached at 1500 bonus Health. )	The percentage scales with their inflated armor total; flat pen barely moves it
Bruiser or duelist in extended fights	The Black Cleaver The Black Cleaver 3,000 gold 200 Health 50 Attack Damage 10% Cooldown Reduction Wicked Edge: 10 Lethality Cleaving Strike: Dealing physical damage to an enemy champion reduces their Armor by 5% for 4 seconds (stacks up to 5 times, up to 25%).	The stacking 5% shred per hit (up to 25%) rewards sustained fights, not a single burst
Mixed team, no clear tank	Lethality early, reassess at your third item	Most early-game armor totals favor flat pen; re-evaluate once the enemy team’s items are visible
Enemy building Thornmail or armor vs. your crit build	Prioritize percent pen over more lethality	Thornmail’s flat armor plus runes pushes targets past the crossover point where percent pen wins

Role matters as much as armor total: an assassin diving the backline cares about the squishy target’s armor, not the tank’s, even if that tank has 300 armor stacked. Build for the target you’re actually going to hit, not the scariest number on the enemy team sheet.

Common Mistakes That Waste Gold

Stacking lethality into a full-tank enemy team. Two or three lethality items against a comp that stacked armor past 150-200 each is the single most common waste: the flat number stops scaling the moment armor passes the crossover point, and that gold should have gone into a single percent pen item instead.

Ignoring that The Black Cleaver The Black Cleaver 3,000 gold 200 Health 50 Attack Damage 10% Cooldown Reduction Wicked Edge: 10 Lethality Cleaving Strike: Dealing physical damage to an enemy champion reduces their Armor by 5% for 4 seconds (stacks up to 5 times, up to 25%). shred is separate from your own penetration. Its 5% armor reduction per stack applies to the target directly, stacking with whatever lethality or percent pen you’re also running. Treating it as “just another lethality item” undersells it: it’s a team-wide debuff, not a personal damage stat.

Building percent pen first into an all-squishy enemy team. If nobody on the enemy side has meaningful armor, a 35% reduction of a small number is still a small number. Lethality does more work there for the same gold, and the extra attack damage or crit on lethality items usually outweighs the marginal percent pen benefit against low-armor targets.

Forgetting that resistances aren’t static. An enemy who buys Thornmail Thornmail 2,450 gold 150 Health 75 Armor Thorns When struck by an Attack, deal magic damage to the attacker and apply 40% Wounds for 3 seconds if they are a champion. or stacks armor runes mid-game can push themselves past the crossover point during the match. Re-check the scoreboard before your last item slot instead of locking in your plan from the draft screen.

Knowing the crossover point in theory is one thing; tracking it live against five enemies whose builds keep changing is another. Tools like buildzcrank read the enemy team’s current items and flag when you’ve crossed from “lethality matchup” to “percent pen matchup” mid-game, instead of leaving you to eyeball armor totals off the scoreboard.

Frequently Asked Questions About Armor Pen and Lethality in LoL

Armor penetration and lethality are not interchangeable despite both being labeled “armor pen” in item tooltips: one scales with the target’s armor, the other doesn’t. Check what you’re actually going to be hitting (a squishy carry or a stacked frontline) before locking in your third item slot, and re-check it again once the enemy’s build is visible mid-game. For the rest of your build order beyond this one decision, the LoL itemization guide covers starting items through tech-slot choices, and the anti-heal items guide covers the other situational pickup that gets built on reflex instead of on a real read of the matchup.