Talk:Armor/@comment-2.82.253.205-20120430165217/@comment-3486816-20120530031251

none other than the fact that it's multiplicatively stacked. Stacking a 20% effect and a 30% effect would lead to a total of .2 + (1-.2) * .3 = 44% damage reduction, as opposed to 50%. As a general rule, take how much total damage reduction you already have (in this case 20% -> .2), subtract it from 100% (leading to 80% -> .8 in this case), then multiply that by the next amount you're adding (in this case 30% -> .3) to get the amount to add to the amount you already have (in this case 20% + (.8*.3 = 24%) = 44%). As you get more and more % damage reduction, it becomes less and less additively effective (for example, suppose you had two sources of 80% damage reduction. The second would only add (.2*.8=16% damage reduction), leading to a still huge total of 96% reduction.