After the 3.13 patch, Zed is still viable in the competitive scene, but will be played in a different way. His ability to all in someone might not be as strong as before, but he can escape easily after taking down a piority target.

Zed is one champion that could be really hard to play in the beginning, but after getting to know his mechanics he can be one really fun and strong champion to play. He can completely delete someone from the enemy team in a span of 3 Seconds if played correctly. Zed has great wave clear and great mobility. He can be played in the top, mid and jungle, but most commonly mid.

Flash - Can be used defensively and offensively. Use flash to close distance with targets or use flash to escape after using your full combo. Always get flash so you can get out of unexpected situations.

Ignite - Allows you to secure kills easily.

Barrier - It really depends on who your against. If you think this will save you or allow you to get a kill, replace Ignite with this.

Cleanse - Depends who your up against.

Ghost - Not recommended.

Heal - Not so good after it's nerf. Barrier is a better choice.

Most of the time get Flash and Ignite.

Contempt for the Weak - Ability for easy farming and finishing low champions.

Razor Shuriken - Can be used for farming and harress. This is zed's highest damage ability, missing this will reduce zed's damage significantly. Always remember the Razor Shuriken that Zed shoots always do more damage then the one shot from the Living Shadow.

Living Shadow - Gap closer. Can be used to jump over walls and dodge skillshots.

Shadow Slash - You can use it with your shadow to slow champions or reduce the cooldown of Living Shadow by hitting an enemy champion with a single Shadow Slash. Living Shadow can use Shadow Slash twice if there's cooldown reduction.

Starting items

Start 1 - Doran's Shield + Health Potion - Start this if you think your opponent will poke you alot.

Start 2 - Long Sword + 2 Health Potion - This start will speed up your item builds such as The Brutalizer or Blade of the Ruined King.

Start 3 - Elixir of Fortitude + 3 Health Potion - This start may delay you from your early core, but will help you win more trades.

Start 4 - Doran's Blade + 1 Health Potion - Make sure you have 2 life steal quints or else this start is too risky.

Early core - Get your The Brutalizer then get a Blade of the Ruined King. This will increase your burst and split pushing potential. The cooldown reduction and armor pen on The Brutalizerworks well on Zed too.

Mid game - Getting a Ravenous Hydra will greatly increase your split pushing potential. You can clear the whole wave using your Ravenous Hydra + Shadow Slash. Get a Last Whisper or Black Cleaver if your opponents are stacking armor.

Late game - Finish off the build with a Guardian Angel and replace your boots with a Mercurial Scimitar or Banshee's Veil if they have alot of magic damage or you are getting lockdown in teamfights.

Situational items
Maw of Malmortius - Replace Ravenous Hydra with this if they have alot of magic damage.

Mercurial Scimitar - Build this if you getting locked down in teamfights.

Banshee's Veil - Build this if they have alot of Ap and you are getting focused or killed in every teamfight.

Bloodthirster - Replace Guardian Angel with this if you no problem surviving teamfights.

Pros

Has insane burst

Has good wave clear

Has a good escape move

Farms easily

Can delete champions if plaed correctly

Does not need mana

Cons

Is hard to use if behind

His ultimate can be countered easily

Zed can last hit pretty easily because of his passive, Contempt for the Weak. Razor Shuriken can be also used to farm creeps at a save distance. Zed can clear waves easily by using Living Shadow, Razor Shuriken and Shadow Slash. Ravenous Hydra makes clearing waves easier too.

1)Poke with [living shadow]], Shadow Slash and then Razor Shuriken. This is your main damage combo in lane. Your main damage output comes from your Razor Shuriken so if you miss that, you wont be doing alot of damage.

2)Remember that if you use Living Shadow to poke, you will not have an escape move if the jungler comes to gank.

3)Everytime your Living Shadow is on cooldown poke with your Razor Shuriken. If the Razor Shuriken hits minions before hitting your target, its damage will be lowered. So try to hit your razor shuriken without hitting minions.

4)After using your combo and your enemy is low enough, switch with your Living Shadow and go in for the kill.

Zed's role in a team fight is an assassin. Try to take down the enemies priority targets such as the AD or AP carry. Flank around to get to their AD carry, do not charge in the frontline to get to their carries, you will most likely get locked down or killed. Never initiate a team fight, wait for your team to initiate then go in for their carries. Try to wait for enemies lockdown/ultimates to be used then go in, Lockdowns suchs as Frozen Tomb and Cease and Desist. Make sure that the enemies do not know where you are, come out of somewhere they don't expect you to be and kill their carries, you can do this with the new Oracle's Lens trinket to check if they have vision of you.

Zed is best with a hard engage team. Pick zed when their carries do not have escape moves, such as Ashe, caitlyn and varus. Beware of cc, if you get lockdown, you will most likely not be able to take down their carries. Lockdowns such as Chain of Corruption, Frozen Tomb and Cease and Desist.
The only adc that can 1v1 zed in my opinion, is Vayne. She has a ability to stun and knock you back. She can also escape and go invis by using Tumble. You should not pick zed if they have ultimates that an lock you dcown in the other team or champions that can move you away from their carries. Most supports will peel for their carries by stunning or knocking you up. You you are getting CC'ed too much get a Mercurial Scimitar.

Zed's ultimate can be used to dodge important ablities your opponents use, such as Fizz's Chum the Waters and Ashe's Enchanted Crystal Arrow. Most of the time it is used to burst down champions.

Way 1 - (R-E-Q) - Use Death Mark, then Shadow Slash and Razor Shuriken. If you can land both of your Razor Shuriken it will do massive damage.

Way 2 - (R-E-Q-W-E-W-Q) - Use Death Mark, Shadow Slash and then Razor Shuriken. Place your Living Shadow in front of them and use Shadow Slash. This will do damage and slow them. Reactivate your Living Shadow to switch places with it and use Razor Shuriken.

Way 3 - (R-E-W-Q) - This is the combo that will do the most damage with Death Mark. Use Death Mark, then Shadow Slash to do some damage and slow them. Place your Living Shadow behind him and use Razor Shuriken. Your shuriken will have a higher chance of hitting as your opponent is slowed by Shadow Slash. If all 3 Razor Shuriken hit it will do massive damage. This method also allows you to dodge abilities. By putting your Living Shadow behind them, you can switch places with it if your opponent tries to hit you with any abilities. If your opponent turns behind and tries to hit you with any abilities, switch back with your Death Mark shadow to dodge it.

Zed's matchups, difficulty rated from 1 - 10. Will be adding more matchups in the future.

Fizz - 8/10 - Fizz is one hard lane for zed. In my opinion Fizz has an advantage over you. You have to reach level 2 or 3 before him or else him can poke you or zone you out of lane. Both of you can dodge each others ultimate if timed correctly. Dodge his Playful / Trickster with your Living Shadow. In conclusion fizz has an advantage over you, but this matchup relies most on skills.

Ahri - 6/10 - Ahri's ultimate Spirit Rush can counter Death Mark quite easily. After using Death Mark, she can dash away from you, preventing you from doing anymore damage. Try not to get hit by her Charm and you should be alright. Try to reach lv 6 before her and you should be able to kill her.

Lissandra - 5/10 - Her ultimate Frozen Tomb counters yours. Early levels you should able to win her in lane. Try to reach lv 6 1st to kill her.

Kayle - 7/10 - kayle is a annoying match up. She might be able to poke you abit in early lv's. She also can prevent you from killing anyone from in her team with her ultimate Intervention. Hardest counter for zed in my opinion.

Orianna - 5/10 - This match up goes in Zed's Favour. Before lv 3 she can harress you abit with Command: Attack. When you get lv 6 you should be able to destroy her. When she uses Command: Attack, you can just switch with your shadows to dodge it and kill her.

Zed - Skilled - A zed vs zed lane is really exciting. You can use Death Mark to dodge his's. This matchup really depends on skills, the one with better understanding of Zed will win.

LeBlanc - 7/10 - Before you hit 3 try to farm and not get too aggressive. Whenever she uses Distortion, try to dodge it and land your full combo on her. Her silence really doesn't do much to you. In conclusion try to dodge her snares and Distortion.

Teemo - 5/10 - Early game Teemo might be able to poke you abit, once you hit 3 use your Living Shadow to harress him. You should be winning trades as blind will not affect your Living Shadow combo.

Diana - 7/10 - Early game try to use Living Shadow to harress her. When you hit lv 6 you should be able to kill her. Try dodging her Crescent Strike in early levels. When she hits six, she has to land Crescent Strike if she wants to burst you down. You can either wait for her to use Crescent Strike before engaging or try to dodge her crescent strike when you engage.

Nidalee - 4/10 - Should be an easy lane if you play zed correctly. A good nidalee player would not want to engage wth you from close range, she would be poking you with spears from afar. Nidalee's all in potential is not as great as yours, try to all in her when you hit 6, you should be able to kill her.

Kassadin - 7/10 - You will lose this matchup if you miss your Razor Shuriken. Your burst is higher than him, try to kill him when you hit 6.

Katarina - 4/10 - Poke her as much as you can as she does not have any sustain for your poke. Try to use Death Mark when she has used Death Lotus.

Heimerdinger - IDK - Omg, I hate this guy. Whenever you lane with a Heimerdinger try to get to lane before minions spawn to prevent him from placing turrets. Do get too aggresive as his turrets will do alot do damage to you. This lane is really boring Just farm and poke him with Living Shadow. When you see Heimerdinger without his turrets, thats your chance to kill him as he cannot do much damage without his turrets.

Xerath - 6/10 - Pre 6 Xerath might poke you in early levels, but once you hit 6, you will destroy him. Once you get a chance to engage with xerath, he will most likely be dead unless he stuns you. You can dodge all his skill shots at close ranged, the only way he can trade back is by using his stun and ultimate. You can either hit lv 6 before him or wait for his stun to be used before engaging.

Riven - 8/10 - Will get more information on this match up - Counter pick to zed. Everytime you go for Creeps, she will Valor to you and stun you with Ki Burst. Try to put Living Shadow behind her when she does that and switch places with it when you tries to stun you. You can also dodge her Wind Slash by using Death Mark or Living Shadow.

Ziggs - Soon

For most of the matchups try to get lv 6 before them.

Although Zed has been nerfed in 3.13 he is still a great champion. Zed has insane burst potential and can be deadly if played correctly. One of the best assasins in my opinion. I hope that this guide helped you to understand and play zed better. Thank you for reading and have a nice day.