Thursday, October 8, 2009

Armor/Magic Damage Reduction

Just thought this would be interesting information. I edited this post because I was told it was redundant information. I will however include the charts for reference.


  1. 10 armor: 9% reduction
    20 armor: 17% reduction
    30 armor: 23% reduction
    40 armor: 29% reduction
    50 armor: 33% reduction
    60 armor: 37.5% reduction
    70 armor: 41% reduction
    80 armor: 44% reduction
    90 armor: 47% reduction
    100 armor: 50% reduction
    200 armor: 66% reduction
    300 armor: 75% reduction
    400 armor: 80% reduction

    As far as I am aware these numbers are also true for MR.

  2. You do know there's a formula for armor/magic resist, right? If you want to know the reduction, the formula is: Armor / (100 + armor).

    Also, the devs have stated that things like damage are actually stored as floats internally; they are not actually rounded to integers as it may seem in the game.

  3. I wrote a GIGANTIC DPS calculator spreadsheet for Tryndamere. It can be adapted to other champions too, but it has Trynd's special stuff all set up right now.

    You can find it here:

  4. Has anyone tested if you get them into negivite magic resist or armour and if that gives you a dmg bonus?

  5. I'm fairly certain that going negative resist does then give a damage bonus.

  6. you cant get into negative resists or armor. even with pene you can reduce MR or Armor to 0 you cant go under 0 even with reduction like Abyssal Scepter cause first calculation is reduction then pene

  7. You can reduce MR and Armor to negative actually. Karthus's wall of pain does it.

    for example, at full rank it reduces magic resist by 35. Most champs have base mr of 30 (without additional mr from runes or defensive mastery tree). They would then take 0.05% additional magic damage (compared to 0mr).

    Couple the wall of pain with an abyssal scepter (-20mr) and fiddlesticks' passive (-10mr) and the champ would have -40mr and take an additional 0.29% magic damage (compared to 0mr).

  8. Maths fail xD. I mean they'd have -35mr (0.26% damage increase)

  9. If you are runed for armor pen, you can have 24 armor pen starting the game at lvl 1, the highest armor at lvl 1 is it is very much so possible to go into negative. Late game olaf with a black cleaver and armor pen bow will 64 flat armor pen plus 43% armor ignor plus the 25% armor decrease and riot already said that the percent ignor is calculated fist so if your fighting a late game adc they will rarely have 100 or more armor, lets say they have 100 so then you take of the percents and that takes them down to 32 armor! Next take away the flat reduction and that lands the lvl 18 adc at a wopping -32 armor!!! The question is whether or not -armor increases your dmg