Hey everyone, so I just joined the Navy and as soon as I get out of Boot Camp there's all these new champs I haven't seen before, anyway as soon as I read that Zed is an assassin and runs off of energy I knew he was the champ I had been waiting for League to come out with.
Without further intro, I give you my build to Zed, with a pulp fiction reference :D
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So Zed is a crazy assassin champ that rocks with the shadows. Cool.
For a mastery setup I went 21-9-0.
In the offense tree you want to pick up masteries that will maximize his damage output while giving your team an advantage throughout the game. One mastery I covet on most champions is Demolitionist, its a great spell because for every hit you do 10 damage to the turret, do 10 hits, you do 100 damage. It adds up throughout the game and eventually wins you advantages when their towers are pushed and your in another lane helping out a teammate.
For the defense tree, I take 3 points in MR, 3 in Armr, and 3 in HP regen. This setup is generally good for solo top, but it works in any lane and while jungling too.
You can always pick a different set of masteries to tailor your own play style.

For runes,
I take Armr Pen reds, Armr yellows, MR per lvl blues, and AD quints
This setup allows for tons of early game damage if you pick up a Long Sword or Dorans Sword because you have 15 armr pen at the start of the game. Armr yellows are standard for solo top, and the MR per lvl blues scale into late game when mages are at their peak. AD quints put your Armr pen reds to good use early game along with a long sword/dorans.

Ignite and Flash are pretty standard on solo top champs, ignite can be replace with Exhaust or flash since W can be used to jump over walls once reactivated.

Ahhhhh, here we are. So many of you may be like wtf items are these. These dont even fit Zed!
Well I'm here to tell you they do, this item build is actually pretty strong on any Assassin while making them a walking tanking monster, and heres why:
So Maw of Malmortius is a great item because its passive provides a great shield when a lot of magic damage is done to you and it blocks a good portion of magic damage. Its second effect provides you with +1 attack damage per 2.5% health missing. Great.
Atma's Impaler provides you with attack damage equal to 1.5% of your max health. Ok.
Now couple both these items with a Warmogs and Frozen Mallet, first off... thats a lot of health, on top of their Armor and MR, so you get pretty tanky. Now you have a walking tank, great. But the added effects allow you to gain a pretty good amount of AD, especially when you have low health, coupled with a Infinity edge, you'll be unstoppable.
Boots can go either way, I normally get Ninja tabi for extra armor since the shield from Maw of Malmortius gives you enough magic defenses.