How Armor and Magic Resist work in LoL, for those that don't know.

Armor and Magic resist naturally increase the amount of damage you can take, that much is obvious, but have you ever noticed how the higher your armor stat, the less the percentage reduction seems to go up?

Well here's, briefly why.

MR and Armor work by effectively increasing your health.

This, naturally, is called effective health.

Specifically, your effective health is increased against a damage type by 1% for every 1 point of resistance.

What this means is simple.
If you have 100 health, and 50 Armor, it will take 150 physical damage to kill you. If you have 100 health, and 50 Magic Resist, it will take 150 magic damage to kill you.

If you have 100 health, 50 Armor and 10 MR, it will take either 150 physical damage to kill you, or 110 magic damage to kill you.

This means that, if the enemy has a spell that damages you for 300 magic damage, and you have 300 health, but just 1 mr, you will survive with 3 health.

This is how armor and magic resist works in a nutshell.

If you want a more indepth explanation, here: https://leagueoflegends.fandom.com/wiki/Armor https://leagueoflegends.fandom.com/wiki/Magic_resistance

This means that, at 100 MR or Armor, you will have 50% damage reduction to either type. But at 200 MR or Armor, you will have 67% damage reduction to either type. At 300 MR or Armor, you will have 75% reduction. At 400 MR or Armor, 80% 500, 83.4% 600, 85.2% 700, 87.5% 800, 89.9% 900, 90% 1000, 90.9%

Because of this, it is literally impossible to get 100% damage resistance.

And that's how resistances work.