So you want to 1v1 the splitpushing Zed with a full pen build?

Last wisper 35% armor pen

Black cleaver 24% armor pen

Draktar 21 Lethality

Youmuus 18 Lethality

Sanguine Blade 18 Lethality

Sudden impact 7 Lethality

Thats 59 % armor pen 64 Lethality

So if you have 156 Armor - (159*0.59) - 64 = -0.13 armor

Hence any amount equal or below 156 Armor means he will deal true damage to you. It actually becomes kinda not viable to even build armor against assassins.

A lvl 18 mage has around 80 armor and 45 from Zhonyas, so he will still take true damage.

At 200 armor you finally get 15% damage reduction. At 300 armor you get 37% damage reduction.

So in the end the tutorial was right after all. It was just ahead of its time. TRIPLE THORN MAIL ASHE is back!