Even though Thornmail has been nerfed in TFT Patch 9.15 when its returned damage was changed from True Damage to Magic Damage, it is still a top tier item for some champions like Braum or Shyvana, in the current meta.
This raises up the question: does Thornmail stack in TFT? Can I put 2 Thornmails on Braum to double the reflected damage? Let’s see what math tells us, with in-game screenshots to back it up.
Does Thornmail Stack in Teamfight Tactics?
Yes, it does. Stacking 2 Thornmails will double the reflected damage (which is now Magic Damage, so the unit’s Magic Resist will reduce the reflected damage). Let’s check some in-game screenshots to back it up.
(*Note: I’m using as an example a game played on Patch 9.14 when Thornmail reflected True Damage because it makes the math easier, not having to count for Magic Resist on the enemy champions, as it’s not calculated in Patch 9.15B when Thornmail reflects Magic Damage instead. Yet, the stacking hasn’t been affected).
Thornmail Stacking Example
Let’s look at a Shyvana with double Thornmails on her. She also has a Phantom Dancer to dodge Crits and benefits from the Dragon buff as well.
She was the last unit standing and she was fighting vs level 2 Zed, level 3 Shen and level 3 Pyke. The opponent had the Ninja Bonus active, having the +80% AD bonus (that was before the Patch 9.15 change granting them AD and AP as well).
Let’s look at the True Damage she reflected and do the math that proves that Thornmail stacks in TFT currently.
Double Thornmail Reflected Damage
Let’s do the math for Shen’s reflected damage first.
He’s level 3, so he has 234 Attack Damage.
He benefits from the 4-Ninja Bonus, which was 80% in that Patch. This gives him 421 AD.
Shyvana has 130 Armor from double Thornmail and Phantom Dancer (40 + 40 + 20) added to her 30 Base Armor.
We’ll use this formula to calculated the mitigated damage (100/(100 + Armor)) dealt by Shen to Shyvana and we get 240 Mitigated Damage.
In the screenshot you can see Shen takes 459 True damage from the stacked Thornmails, which is pretty close to the double of the mitigated damage 480. This difference could come from the Armor calculation formula, which might work differently for TFT than it does for LOL.
This confirms that Thornmail stacks in TFT.
Another example for 1 Thornmail
This is just for reference, to see the difference in reflected damage when having a single Thornmail.
As you can see, Vayne takes 35 True Damage reflected by the Shyvana’s Thornmail. Let’s see if the number adds up.
Vayne is level 2 and she has 72 Attack Damage.
Shyvana has 90 Armor (40 from Thornmail, 20 from Phantom Dancer and 30 Base Armor).
Using the same formula from the link above, we get a mitigated damage of 35, which is exactly what’s shown in the screenshot as well.
Conclusion: Does Thornmail Stack in TFT?
The examples above confirm that double Thornmail stacked on a champion will reflect 200% of the mitigated damage.
Why double Thornmail works great on Braum
Since Thornmail reflects damage based on the mitigated physical damage, it works perfectly on Braum because when he has his shield up, he mitigates 70/80/90% of the damage. To that you can add his high Armor base and the Armor from the 2 Thornmails. This makes him a top damage dealer in many comps.
The screenshots above are from this video (again, this was before patch 9.15 when Thornmail did True Damage and 4-Ninja bonus was 80% AD):