|Passive||Unique: On being hit by basic attacks, returns 30% of damage, before any reductions such as armor, as magic damage.|
|Menu||Defense > Armor|
|Item cost||2200g (1180g)|
- 100 armor = 2000g
- Total Gold Value = 2000g
- Tanks benefit most from , particularly when the opposing team has high basic attack damage output. League of Legends calculates Thornmail's reflected damage before armor reduces the damage. This means you can reflect more damage than you ultimately take if you have at least 234 effective armor (i.e. after reductions and penetration).
- is best used to counter champions that mainly rely on basic attacks such as Tryndamere and Ashe.
- is often overshadowed by the other two high armor items, and , because it benefits only the wearer instead of the entire team and only provides armor.
- Because of these reasons, it is generally acquired only as a counter against certain champions or against an AD heavy team.
- Champions such as Rammus, Galio and Shen can make great use of the passive effect due to their ability to taunt enemies, forcing enemies to attack them with basic attacks.
- Thornmail deals magic damage, and so the target's magic resistance will reduce the damage returned. Life steal is another option to reduce its overall effect.
- reflects both physical and magic damage; the only determining factor in its trigger is whether the attack is defined as proccing on-hit effects. For example, Warwick's Infinite Duress deals only magic damage, but still procs unique passive.
- Blind counts as a form of damage mitigation and is thus applied after , i.e. damage is still reflected even though none is actually done.
- Damage returned from will break passives which are removed by champion damage such as Move Quick or Strut. It will also drag tower aggro.
- Fiora's ultimate does on-hit damage based on her maximum damage and calculated armor pen. If is built quickly against a snowballing Fiora, she can seriously hurt herself or even suicide against a champion utilizing it, assuming she doesn't have much lifesteal.
- A Poppy that has shielded herself using Diplomatic Immunity will still reflect the full amount of damage to the non-targeted enemies, despite taking no damage herself.
- It is one of the few items mentioned in The Proving Grounds tutorial.
- Currently, this item offers the largest amount of armor, being slightly above 95 armor.