Hello and welcome to my Zed guide, I am DeathGun1.
Before you jump on and say that I have no experience and no say on this champion because I don't play ranked and that I was a silver player
I will just let you know that I have over 170 K mastery points on him As well as mastery level 7 on him.
So I feel I get some say in him, but you high elo gods can correct me if you want.

NOTE: I will update this guide in the futur

So I would like to start with runes.
A standard rune page for Zed would be any rune page for assasins.Which is: Armor Penetration Marks,Armor Seals, Magic resists Glyphs and Attack Damage Quints.
But for me, I got used to the AD Marks, Armor Seals,MR Glyphs and AD Quints.
I feel Zed can get enough Armor Pen. with items itself, so I use my own page.
Let me know what you liked better.

For masteries, I take ThunderLord's Decree to add onto Zed's bursts, but recently a new Keystone is also used, Stormraider's Surge. Faker used it and RedMercy made a video about it and you should definetly check it.

Link: https://www.youtube.com/watch?v=AkHhg2RTGiM

Pros
[*] Farming
[*] Mobile
[*] Split pushing
[*] Poke
[*] Harass
[*] Wave clear
[*] Energy instead of Mana

Cons
[*] Vulnerable to CC
[*] Melee
[*] High learning curve
[*] Zhonya counters you

I feel Zed's kit is just unique in it's own way, I just love the get it, burst and get out unscathe.
His ultimate is just amazing for dodging a threatening abilites like a Yasuo's tornado, Riven's Ult, Fizz's Ult, etc.

His living shadow and the ability to swap shadows is so unique and can mess with peoples' heads.

I feel like Zed is a champ that doesn't really fall out of meta and can be played by anyone.
If you can adapt to the meta, he is always strong in my opinion.