I've been thinking of spicing up my Rammus play with some variance, and one thing I've been looking at is the armor Leviathan, which grants health in a snowball fashion. At max stacks, it reduces damage taken by 15% (which sounds similar to the 4% reduction you can get if you have enough Defense Masteries). As a tank, and as Rammus specifically, I tend to get a lot of assists which helps build up to that 15% reduction.

That got me thinking, how does this interact with some of the various other methods to reduce damage, though? There are at least 3 methods I know of.

  • Armor/Magic Resist - Detailed quite thoroughly here.
  • Reduce damage by fixed number - Amumu's Tantrum has a passive that does this, and there's also a Mastery that affects this.
  • Reduce damage by percentage - The aforementioned Leviathan item and the Mastery.

What is the order in which these effects are applied? Do the latter two apply to the damage after armor/magic resist is factored in, or do they alter the damage prior to calculating armor/magic resist? Are there any other methods of damage reduction that have their own special effects for this?

If it's not too far off to simultaneously address, do damage amplifying effects like Vlad's ultimate counter the corresponding damage reduction methods, or do they multiplicatively stack with the results at some stage?

This question covers how normal attacks benefit, but it doesn't happen to cover these specific effects and how they synergize with each other.

  • 2
    Just a minor point: The damage reduction abilities (such as Alistar's ult) have been patched out to no longer reduce true damage abilities. Commented May 31, 2011 at 16:18
  • @Raven Makes sense, thanks. I expect true damage just does straight up did X damage, not going through any calculations? Which is why I tend to be a literal feeder against an opposing Cho'Gath...
    – Grace Note
    Commented May 31, 2011 at 16:22
  • My attempts so far to test this have been thwarted by a corrupt installation. Though I can confirm flat reduction happens after armor reduction. Commented May 31, 2011 at 16:44

1 Answer 1


Okay, from my experiments, it goes:

Armor/MR reductions <--> Percentage Reductions
(They stack multiplicatively, so order is irrelevant)

Flat Reductions

This makes sense, since if flat reduction was the first thing applied, after armor, it may have failed to provide a benefit at all (since, for instance, the difference between 50 * 27% and 48 * 27% is minute at best. 50 and 27% being the base attack damage of Ezreal and the armor of Amumu, my two test characters.)

Shields act as health, and damage done to shields is likewise reduced by armor / magic resist. (Meaning shields on tanks can generally absorb more punishment than shields on squishies)

  • Out of curiosity, how did you test this? Did you have a friend and you created a custom game together? Or is there actually some sort of match-up utility you can use?
    – Grace Note
    Commented Jun 1, 2011 at 12:17
  • @Grace I used my brother and we created a custom game together. It worked out well, 'cause he had already bought amumu. Commented Jun 1, 2011 at 15:14
  • Ah. I'd say "darn", but in the end, I've also got a sibling. ♪
    – Grace Note
    Commented Jun 1, 2011 at 15:20
  • 1
    Note that abilities that scale to percentage of health (Vayne's W, Elise's Qs, and Kog'Maw's W come to mind) will not increase damage when a shield effect is on their target.
    – Yuuki
    Commented Dec 15, 2012 at 3:39

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