Armour

From the wiki:

Examples:

25 armor → × 0.8 incoming physical damage (20% reduction, +25% effective health). 100 armor → × 0.5 incoming physical damage (50% reduction, +100% effective health). -25 armor → × 1.2 incoming physical damage (20% increase, -16.67% effective health)

this link has the actual calculation but i don't think i can just paste that here because of the type of element it is on the site. https://leagueoflegends.fandom.com/wiki/Armor

Cracks knuckles. Let's get "mathy"

So the basic formula for armor (and MR) is.....

X = Armor Y = Damage (AD) Z =Actual DMG

DMG = [100+(X+100)] Let's plug in a number for armor like 50.

Z= Y * [100+(50+100)] Simplified Z = Y *100/150 Z = Y * .66666667

What that means is if I hit you with 1000 (Replace Y with 1000) damage and you have 50 Armor you will reduce my damage by 33.3333333%

So 1000*.666667 = 667 Damage to someone with 50 Armor.

If you increase to lets say 100 armor. It cuts the damage in half because.. 100/(100+100) = .5

Z=Y*X Z=Y(1000) * X(.5) So 1000 dmg does 500.

That's how the math checks out. Shyvana nerd out!

For your Garen Question

100/(100+35) = .74 100*.74 = 74 damage taken.

For TFT it's the same.

every % of resistance increases your health pool of that damage type by 1%.

if garen has 1000 hp and 35 armor, he has 135% = 1350 effective health against physical damage. thats why contrary to popular belief, there are no diminishing returns on resistances.

you will have a breaking point in the equation where health becomes more effective than buying armor, when you already have a lot of armor, and one where armor becomes more effective when you already have a lot of health.

but the relative gain is the same for each % point of resistance. be it the first or your 300th point of armor.