No Ultimate Spellbook-specific changes; identical to the Summoner's Rift version.
Effects
Unique Passive · Thorns
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.
Patch history
25.5
Bug Fix: Corrected a tooltip issue.
14.21
Bug Fix: Thorns' tracker now displays the proper post-mitigation damage values instead of pre-mitigation ones.
14.20
Armor reduced to 75 from 80.
Thorns base damage increased to 20 from 15.
Thorns bonus armor ratio reduced to 10% bonus armor from 15%.
Unique Passive - Thorns: When struck by an attack, deal 10 (+ 10% bonus armor) magic damage to the attacker and inflict them with 40% Grievous Wounds for 2 seconds if they are a champion. Immobilizing enemy champions also applies 60% Grievous Wounds for 2 seconds.
Limited to 1
9.8
Grievous Wounds duration increased to 3 seconds from 1.
8.4
Bug Fix: Now correctly applies the cripple debuff to minions and monsters attacking its owner.
Removed Passive: Reflects 15% of the physical damage taken (+ 25% bonus armor) from basic attacks and on-hit effects back to its source as magic damage.
6.14
Added to the Twisted Treeline.
5.16
Total cost increased to 2350 g from 2100 g.
Reflected damage reduced to 15% from 30%.
New Effect: Reflected damage now deals (+25% bonus armor) bonus damage.
The armor ratio will be affected by flat armor reductions down to 0 armor - while percent armor reductions will be ignored for the purpose of calculating bonus damage.i.e. The Black Cleaver will not reduce the reflected damage by reducing your bonus armor but a level 5 Puncturing Taunt will reduce the reflected damage by 6.25(25% of 25).Negative armor values will be treated as 0. Armor penetration will not affect the ratio.
4.20
Item cost decreased to 2100 g from 2200 g.
Combine cost decreased to 1050 g from 1180 g.
3.10
New icon.
V13.1b
Undocumented: Armor increased to 70 from 60.
Thorns armor ratio increased to 25% bonus armor from 20%.
Grievous Wounds strength increased to 40% from 25%.
Removed: Immobilizing effects on enemy champions no longer inflict them with Grievous Wounds for 3 seconds.
V1.0.0.82
Damage return increased to 30% from 25%.
V1.0.0.63
Recipe cost increased to 1000 g from 600 g.
Armor increased to 100 from 70.
Damage return increased to 25% from 20%.
V1.0.0.152
Item cost increased to 2200 g from 2000 g.
Combine cost increased to 1180 g from 1000 g.
V1.0.0.151
Removed from the purchasable item list on Twisted Treeline.
Unique Passive - Thorns: Upon being hit by a basic attack on-hit, reflects 25 (+ 10% bonus armor) magic damage, while also inflicting Grievous Wounds on the attacker for 3 seconds.
Unique Passive - Cold Steel: When hit by basic attacks, cripples source's attack speed by 15% for 1 second.
New Passive – Thorns: Upon being hit by a basic attack, reflects magic damage equal to 25 (+ 10% bonus armor), inflicting Grievous Wounds on the attacker for 1 second.
New Passive – Cold Steel: When hit by basic attacks, reduced source's attack speed by 15% for 1 second.
+
+
+450 g = 2,450 g