I totally agree, i know a little more now. I'm gonna redo this guide

I made two points:
1. Last Whisper has terrible synergy with your build and should be removed.
2. You went a bit overboard with the armor pen, and could probably lose Black Cleaver or something.

I'm not so sure about Last Whisperer and The Black Cleaver, but the rest is great

%pen is applied after flat pen, meaning it will be less effective the more flat armor penetration you have. Stacking Last Whisper with flat armor penetration and reduction like Zeke's Harbinger, Black Cleaver, Youmuu's Ghostblade, Ragnarok, Sunder and Greater Quintessence of Desolation is a very bad idea.

Also, the amount of armor pen you have is a bit overkill. If you're going to stack that much flat pen, at least get rid of Last Whisper.