Thornmail

Stats

Values as the League of Legends Wiki's item data lists them, for every mode; the data doesn't state their units.

Effects

• Thorns (unique): When struck by a basic attack on-hit, deal 20 (+ 10% bonus armor) magic damage to the attacker and, if they are a champion, inflict them with Grievous Wounds for 3 seconds.³

Arena changes

• Armor changed to 60.
• Health changed to 300.
• Thorn base damage changed to 20.
• New Effect: Dealing physical damage to enemy champions also inflicts them with Grievous Wounds for 3 seconds.
• New Effect: If the target heals for a total amount that is over 60% of their maximum health while continuously afflicted with Grievous Wounds, the strength of the healing reduction is increased to 80%.⁴

• For Shyvana with Dark Steel Talons, build Thornmail for antiheal and armor synergy.⁵

• Divine Sunderer's Spellblade heal is granted before Grievous Wounds from Thornmail's Thorns is applied.⁶ Patch unknown
• Thornmail's reflected damage triggers each time Double Tap applies its on-hit effect, making Thornmail a counter to Double Tap.⁷⁸⁹
• With enough haste, Braum can cast W on himself again before the first W buff runs out, gaining more armor; with Thornmail, enemies can kill themselves by attacking him.¹⁰