This guide is not complete. Upcoming changes include:

1. making it pretty.
2. Providing video links for each combo.
3. mathematical comparison of damage from each build.
4. More detailed Laning sections.
5. Early, mid, and late game sections.
6. Proof Reading!

I am new to guide writing, so I will say that this is a work in progress. That being said, After playing quite a few matches with Zed, I want to share what I've learn with everyone else.

Zed is an energy based, AD, assassin. He is designed specifically to initiate against and kill single targets.

The two ways to do massive amounts of damage with Zed are attack Speed and Attack Damage nuking. Both methods take advantage of the damage created during the 3 second mark from Death Mark to burst down an opponent.

Nuker:
The nuker uses raw attack damage to empower his abilities to do massive damage in a very short period of time. When he leads with Death Mark, all damage done in those 3 seconds is added back again at -50% plus a base damage. In essence if you did half the opponents max health in damage during those 3 seconds it is an automatic kill when the base damage plus the 50% damage proc. One great feature of this build is that most of his damage is done through his abilities. This damage is not returnable by thornmail.

AS:
The attack speed build for zed is designed to allow him good movement speed so he does not have to use his ultimate to close. Instead he can either use Shadow Slash to slow them or catch them on his own. When he does he cast Death Mark and racks up as much damage in auto attacks during the 3 seconds. Note Casting Razor Shuriken is not recommended during this time as the small cast animation does delay auto attacks.

Razor Shuriken: Zed and his shadows cast a skill shot that hits all enemies in a line for AD. Damage is reduced after the skill shot passes through the first target, and the damage is reduced further for each shuriken that hits the same target. Coupled with Death Mark and Living Shadow, this is Zed's main damage dealer. Energy is returned if a Shadow hits an enemy with this ability. The targeting for the shadows takes some getting used to. They will always fire in the direction you do, unless you have your cursor over an enemy (in which case they fire at the same target as you).

Living Shadow: Zed Cast a Shadow of himself a short distance away. (about the distance of Flash). Living Shadows mimic both Razor Shuriken and Shadow Slash. Also passively increases his AD by 5% per skill level. Casting it again while the shadow is alive causes you to switch places with it.

Shadow Slash: Zed hits all enemies, in a short diameter, around him for AD. Enemies hit by a shadows Shadow Slash are slowed by 40%, this effect stacks twice. Enemies only receive damage from one shadow's ability. This spell also lowers the CD on Living Shadow by 1 second per enemy hit.

Death Mark: Zed dashes toward a target becoming untargettable, once he reaches the target he deals damage, applies a mark, and spawns a Living Shadow behind the target. After 3 seconds the mark ignites and deal a base damage plus a percentage of the damage done to the target during the mark's duration. Casting this spell again while the shadow is alive will cause you to switch place with it.

There are two types of builds that work well with Zed both rely on the damage done during the mark period to burst down an enemy. The two ways to achieve this are by going strait AD or by going AD, AS, and some health. First i'm going to list the pro's and con's to Zed as a whole, and then i will compare the two build types.

My rune choice is based on the fact that most of Zed's damage comes from his abilities. This means critical strikes don't help nor does attack speed (except for Death Mark but we will get to that later.) The only option left is to make his abilities hit harder, so armor pen all the way (unless you are following the AS build). The only other option is AD runes, but Zed is normally hitting squishy AD or AP carries. Which means that Armor Pen is a lot more effective.(dropping a person to 10 armor from 50 armor will add about 25% more damage to them, compared to dropping someone from 100 armor to 60 which only increases damage by about 10%).

As i said there are two ways to deal massive ammounts to damage. Pure AD or AS.

Zed's Core Build AD:
Bloodthirster, Infinity Edge, Yoummu's Ghostblade, Ionian Boots of Lucidity

The point in this build is to maximize AD while gaining enough cool down reduction to cast Shadow Slash twice in a shadows time to live.

Zed's Core Build AS:

Bloodthirster, Infinity Edge, Phantom Dancer, Berserker's Greaves, Frozen Mallet

The point in this build to to simply increase auto attack damage by increasing attack speed and AD. Also these items give you just enough survivability to live the 3 seconds it takes to ignite the mark.

I keep the same skill sequence for each role. Simply because the benefits of ranking Living Shadow are gained through the item build anyway (cool down reduction, Attack Damage). Also the 5% per level in AD wont make that much difference early or mid game, but the increased damage and slow from the two other abilities makes a lot of difference. Also using Shadow Slash while jungling will lower the CD on Living Shadow

You should take a level in Razor Shuriken first and max it first. Then take Living Shadow at level 2, max it last. Max Shadow Slash second, and of course get a level in your ult when available.

When juggling you do more damage over time with Shadow Slash, so get it first and still max it second.

Zed's greatest attribute is his mobility. I chose Teleport and Flash to increase that even further.

A Teleport, Flash, Death Mark combo and get you a lot of kills during the match if an enemy champ is hanging around minions or wards low. Flash also serves as an escape option when using the nuker build.

Other viable options include:

Ghost - will help you get in range of Death Mark.
Exhaust - helps with escapes and securing your kills.
Ignite - always useful for that last bit of damage (does not proc with Death Mark)
Smite - must have if jungling.

Poking Combo:

Living Shadow, Shadow Slash, Razor Shuriken

Nuking Combo:

Death Mark, Living Shadow (past enemy), Shadow Slash (when enemy walks between both shadows), Razor Shuriken, (when he walks past the farthest one), Shadow Slash, Living Shadow (to switch places)

If the enemy doesn't attempt to flee then simply cast all abilities one after the other.

Escape/AS Combo:

Death Mark, Living Shadow (away from the fight) Shadow Slash, Razor Shuriken, Auto attack till mark ignites. Then chose to continue fighting or cast Living Shadow again for escape.

Now its time for the fun. Here is my disclaimer. This is how I lane. If you dont like to be aggressive at laning then you probably wont like my guide.

As i stated before take Razor Shuriken first and use it to poke as much as you can. You entire success early game is dependent solely on your ability to hit this skill shot. Miss it often and you will fail. Hit often and you will succeed. Zed's passive Contempt for the Weak will get you all the last hits you need, so focus all abilities on harassing.

When you reach level three you should be able to kill most opponents with a simple W, E, Q combo, otherwise keep harassing and farming. If you are getting pushed from you last hits use your shadows to get them.

If the opponent starts playing defensive use your shadow as an extension of yourself. Read the abilities section to see how your shadows targeting works.

The goal here is to not let your opponent breath. If he backs then push the tower. If he fights then burst him and escape. Don't let him have anything for free. If he wants to farm he takes a shuriken to the face.

Not buying wards as solo top is bad no matter what, but Zed can kinda get away with it if he is smart. I don't recommend it, but it can be done.

Zed will of course start at the Red buff(no mana and a melee champ). Afterwards get wraiths then golems. The key to jungling well with Zed is to cast your Living Shadow and spam Shadow Slash as much as possible. This will decrease the CD on your shadow to get it ready to clear the next camp.

Next gank the nearest lane. Then move to wolves and give blue buff to your AP carry if you can. if you still have the health clear golems with smite and then wraiths. You should have enough gold to purchase Madred's Razor.

Return to your jungle gank runs and repeat till laning phase is over.