User blog comment:KeithCornell/My changes to Regenerations and other stats/@comment-973379-20150405150822/@comment-973379-20150407184759

170, 200 or 400.. When your attack have all this penetration(and you can't just nerf non-crit penetration, cause AD casters, who doesn't build crit, need it too)

100*0.25*0.94*0.35=15

200*=30

400*=61

So thornmail will give you... 15 armor. Ofc crit isn't 100%, so actual value will be 100*0.25*0.65*0.94*0.55 + 100*0.65*0.94*0.45 = 35 armor(assuming 55% crit from IE+PD). So while overall damage from ADC will be lower, armor won't be able to reduce it that much.. So will become useless, noone want to pay for 100 armor and get 35.

I don't deal with absolutes. I deal with math. And while I don't currently know exact % for lifesteal, I can guess that it's something like 5-10% of base hp on BotRK, so 100-200 for WW. Coupled with his passive and 2.5 AS it's (100+50)*2.5=375 per second. While currently it's 100*0.15+50=65 per AA, 65*2.5=160. And this is the same for many bruisers. As if they aren't strong already... As I said.. Better nerf Irrelia(you can't even kite her).