Understanding Champion Damage Types: Physical, Magic, True Damage, and How to Build Against Them

League of Legends has three fundamental damage types: physical damage, magic damage, and true damage. Physical damage is mitigated by Armor. Magic damage is mitigated by Magic Resistance (also called MR). True damage bypasses all defenses and deals exactly its stated value regardless of any armor or magic resistance. Understanding which damage type a champion deals — and in what proportion — is the prerequisite for making smart defensive item choices. Building armor against a mage or MR against an AD assassin is a fundamental mistake.

Physical damage comes primarily from basic attacks and most AD-scaling abilities. AD champions like Draven, Zed, and Caitlyn deal predominantly physical damage. Their damage is reduced by your armor value: at 100 armor, you take 50% of physical damage; at 200 armor, you take 33.3%. Armor scales non-linearly — each additional armor point provides diminishing percent-damage reduction, but increasing amounts of effective HP. Building armor against a full AD composition is always correct; building more armor beyond the first tank item has diminishing returns that must be balanced against other stats.

Magic damage comes from AP-scaling abilities and some on-hit effects. Mages like Lux, Syndra, and Orianna deal nearly pure magic damage. Certain AD champions with magic-damage abilities — like Corki (whose basic attacks deal 80% magic, 20% physical) or Kayle (whose empowered autos deal magic damage) — create hybrid damage profiles that are intentionally difficult to itemize against. Magic resistance reduces magic damage identically to how armor reduces physical: 100 MR means 50% reduction, 200 MR means 33.3% reduction.

True damage is the most feared damage type in League because it cannot be mitigated by any defensive stat. Champions that deal significant true damage — Vayne (Silver Bolts), Fiora (Dueling passive), Camille (Hextech Ultimatum), Garen (Villain mechanic) — are inherently threatening to tanks because their high armor and MR do nothing against the true damage component. A Vayne with fully stacked Silver Bolts deals true damage equal to 9–15% of the enemy's maximum HP — which scales upward with the target's HP, making tank itemization actively counterproductive against her.

True damage implications for itemization: if the primary damage dealer on the enemy team deals significant true damage, defensive stats against that champion's physical or magic damage component are less valuable. Against Vayne, stacking HP is often better than stacking armor — she deals true damage based on your max HP, but her physical autos still deal reduced damage against armor, so some armor helps but HP amplifies the Silver Bolts damage. Against Fiora, defensive positioning and not being marked by her passive Vitals is more impactful than itemization, as Vitals deal true damage that items cannot reduce.

True damage interactions with shields are important. While true damage ignores armor and MR, it does not ignore shields. A Sterak's Gage shield, a Lulu W shield, or a Janna E shield will absorb true damage before it hits your HP bar. Against true-damage-heavy compositions, shielding abilities and items like Immortal Shieldbow (which grants a substantial shield when you drop below 30% HP) provide meaningful protection. This is a nuanced but important itemization consideration when facing champions whose kit center around true damage.

Armor reduces physical damage by a percentage calculated as: Damage Reduction = Armor / (100 + Armor). At 50 armor (base for many champions plus a cloth armor), you take 33.3% less physical damage — effectively 1.5x your physical HP. At 100 armor, you take 50% less physical damage — 2x physical HP. At 200 armor, you take 66.7% less — 3x physical HP. This formula means early armor purchases provide a high percentage of the total benefit; reaching 300+ armor has diminishing marginal value unless the enemy has armor penetration.

Armor penetration counters armor stacking. Flat armor penetration (from items like Serylda's Grudge or Mortal Reminder) reduces the target's effective armor by a fixed number — at 30 flat penetration, a 100-armor target effectively has 70 armor. Percent armor penetration (from Lord Dominik's Regards, Black Cleaver stacks, or Last Whisper line items) reduces armor by a percentage — at 35% penetration, 200 armor becomes effectively 130. High-armor targets are specifically countered by percent penetration, which is why Last Whisper is a reactive purchase against enemies building Thornmail or Frozen Heart.

Thornmail and Frozen Heart are the two dominant armor items with active effects beyond raw mitigation. Thornmail reflects a percentage of physical damage taken as magic damage back at the attacker and applies Grievous Wounds (50% healing reduction). It is specifically purchased against ADC or healing-dependent fighters. Frozen Heart slows the attack speed of nearby enemies by 20%, directly nerfing auto-attack-heavy champions. Understanding which armor item is correct — raw HP/armor for sustain, Thornmail for healing counters, Frozen Heart for attack-speed counters — is situational itemization at its most impactful.

Magic resistance scales identically to armor: 100 MR means 50% reduction, 200 MR means 66.7% reduction. Most champions have between 32–52 base MR, making them moderately vulnerable to magic damage early. AP mages who hit level 6 with their first Amplifying Tome deal burst damage that feels overwhelming, but this damage is specifically countered by MR items. An early Null-Magic Mantle (15 MR for 450 gold) provides immediate magic damage mitigation and is one of the most efficient early defensive purchases against burst mages.

Spirit Visage and Force of Nature are the dominant MR items in the current game. Spirit Visage grants 60 MR plus healing amplification — ideal for champions who rely on lifesteal, spell vamp, or external heals (like Soraka or Yuumi) to sustain. It is the go-to MR item for melee juggernauts and fighters facing AP threats. Force of Nature grants 70 MR plus movement speed and a stacking magic damage reduction passive, making it ideal for champions who receive multiple magic-damage hits quickly — frontline tanks fighting LeBlanc, Brand, or Lux.

Adaptive Helm (now Hollow Radiance in later seasons) specifically reduces repeated magic damage from the same source — it is purchased against champions who deal frequent, multiple-hit magic damage: Brand (whose passive dot hits repeatedly), Rumble (continuous flame damage), Ryze (rapid Q casts). For burst mages who deal one large damage event (Syndra, Orianna R, Lux R), generic MR items are more efficient. Identifying whether the enemy's magic damage comes in bursts or sustained waves helps you choose the right MR item.

The hardest compositions to itemize against are mixed-damage compositions where the enemy team splits evenly between physical and magic damage sources. If the enemy team has a Zed mid (AD), an Ashe ADC (AD), a Nautilus support (magic), a Hecarim jungle (mixed), and a Garen top (AD-heavy), you can safely build armor as a primary defense. But if the composition is Zed, Corki ADC, Lux support, Morgana jungle, Rumble top, the magic and physical damage split is roughly 50/50, and building only armor leaves you glass to the magic damage.

The classic counter-itemization challenge: your own tank should decide between armor and MR based on which damage type is higher on the enemy team and which specific champions are targeting you. If you are playing Malphite and the enemy has 3 AD champions, build armor first. If the enemy has 3 AP champions, build MR first. If the composition is split 2/2/1, build whichever side represents the most immediate threat — typically the assassin or marksman whose job is to kill you before the fight develops.

Hybrid-damage items solve the mixed-damage problem partially. Wit's End (on-hit MR shred plus AP damage on hit) was designed for hybrid damage dealers who build attack speed. Riftmaker and Liandry's Torment are designed for AP champions dealing sustained damage, but their passives scale off enemies' maximum HP in ways that interact differently with resistances. The game's itemization system is deliberately designed so that no single item perfectly counters a fully mixed composition — requiring players to make judgment calls about which resistances to prioritize.

Grievous Wounds is a debuff that reduces all healing received by 40% (or 60% when applied by certain abilities). It counters lifesteal, spell vamp, champion heals (Soraka Q, Yuumi W), and regeneration effects. The champions who rely on healing for sustained tankiness — Dr. Mundo, Volibear, Vladimir, Aatrox, Swain — are specifically vulnerable to Grievous Wounds. In a game where the enemy has a fed Dr. Mundo regenerating to full HP every few seconds, building Grievous Wounds is not optional — it is the only way to actually kill him.

The primary Grievous Wounds items are Thornmail (tank, applies on taking physical damage), Chempunk Chainsword (fighters/assassins, applies on dealing physical damage), Executioner's Calling (ADC early component, applies on dealing physical damage), Morellonomicon (mages, applies on dealing magic damage), and Chemtech Putrifier (supports, applies when you heal an ally). Each is designed for a specific role and champion type, so there is always an appropriate Grievous Wounds item for every role. Failure to buy one against heavy healing compositions is one of the most common itemization mistakes in solo queue.

The interaction between Grievous Wounds and healing percentages is multiplicative. A Vladimir with 500 HP regenerated per ability rotation without Grievous Wounds heals 500 HP. With 40% GW, he heals 300 HP. With 60% GW (max application), he heals 200 HP. Over a 10-second fight where he casts 5 abilities, that difference is 1,500 HP healed vs. 600 HP healed — a 900 HP swing that likely determines whether he lives or dies. The earlier Grievous Wounds is applied in a fight, the more total healing is denied over the fight's duration.

Armor and magic penetration items are offensive items that make your damage ignore a portion of the enemy's defensive stats. As a damage dealer, you should purchase penetration items when enemies are building resistances against you. If the enemy top laner just bought Thornmail (armor item), buying Last Whisper (40% armor penetration) makes your physical damage significantly more effective. If the enemy mid laner is stacking Banshee's Veil and Zhonya's Hourglass (both of which include some MR), buying Void Staff (40% magic penetration) increases your effective damage.

The timing of penetration purchases matters. Early in the game when enemies have only base resistances (typically 30–50 MR and 50–70 armor), penetration items provide less value because there is less resistance to penetrate. As the game progresses and enemies invest in defensive items (100+ MR, 150+ armor), penetration scales proportionally. A Sorcerer's Shoes (18 flat magic pen) is most valuable in the early game when you are fighting champions with low MR. Void Staff (40% magic pen) is most valuable in the mid-to-late game against tanks building Abyssal Mask or multiple MR items.

Lethality is the AD equivalent of flat magic penetration, effectively reducing the target's armor by the lethality value for your attacks. At level 18, 18 lethality effectively reduces enemy armor by 18. Items like Duskblade of Draktharr, Edge of Night, and Serylda's Grudge provide lethality and are the bread-and-butter of assassin builds. Building a full lethality kit against a heavily armored frontline is inefficient — percent penetration (Last Whisper line) is superior there. But against squishy targets with base resistances, lethality maximizes burst damage because the flat reduction punishes low armor most severely.

Itemization is not a fixed build order — it is a dynamic response to what the enemy team is doing. In champion select, identify the primary damage type of the enemy team: is it predominantly AD (multiple auto-attack carries, fighters), predominantly AP (multiple mages, AP supports), or mixed? This initial read determines your first defensive item. In the first 10 minutes, refine the read based on which enemies are getting kills and which items they are building. A Zed at 4/0 with Serylda's is a higher armor-penetration threat than at 0/2 with Longsword.

The adaptive build includes a reactive item slot — one item slot reserved for whichever defensive or situational item the game demands. If you normally build five damage items as a carry, make item five a reactive slot: buy Quicksilver Sash against Mordekaiser or Malzahar (who suppress you), buy Maw of Malmortius against burst AP assassins, buy Galeforce for an extra dash against catch-heavy compositions. The reactive item slot acknowledges that no pre-game build order perfectly fits every game context.

Reviewing your item builds in post-game is one of the fastest improvement tools available. Did you die repeatedly to an AP assassin while building 0 MR? Did you build Void Staff against a team with base MR when it provides minimal benefit? Identifying these mismatches in hindsight and asking "what should I have bought instead?" develops itemization judgment that you carry into future games. Over dozens of games of post-game item review, your builds will naturally converge toward situationally correct choices rather than defaulted build orders that do not adapt to game context.