http://www.leagueoflegends-wiki.com/lol/guides/faq"Q: How does armor and magic resistance work?
Every 1 armor means the damage it takes to kill you is extended by 1% of your hitpoints. At 100 armor, it takes 100% more damage to kill you, ie it requires double damage, ie you're taking half-damage. At 300 armor you're taking 25% damage, etc.
Is this diminishing returns? Not really. The damage it takes to kill you is scaling linearly. If you have 1000 hitpoints, then each point of armor means you can take 10 more damage before dying. And this is true no matter how much armor you have (aside from rounding errors). So in that sense, it's linear, and there are no diminishing returns.
Magic resistance works in the exact same fashion, except it does so against spells only. There is no overlap between armor and magic resistance at all. (Ex. Having 500 Armor would have no impact on spells, having 500 Magic Resistance would have no impact on physical attacks)"
102 armor => 50% armor reduction.
Es decir, 100 de armadura => Tienen que hacerte el doble de daño para matarte, ya que sera reducido a la mitad. 100 de armadura => 100% mas de daño que tienen que hacerte.
Es asi de simple. 1 de armadura / MR => 1%
50 => 50% (Mas de daño necesario para morir, no 50% reduccion de armadura) => 33% Reduccion dmg
100= 100% daño extra necesario => 50% reduccion daño
150 armadura => 150% daño extra necesario => 60% reduccion daño
Etc.
Es lineal, punto.