I might mention it later but the goal of this build is not to be op and have epic damage, but to have very good damage and survivability partnered with 2 offensive summoner spells.
That being said, this is a realalistic build for ranked players and will work in almost any patch. This is my cooki cutter for ez.

Since patch updates, armor pen is not as effectivve.

1.Armor pen May proc on q. *but* it does not add damage to q or R.
2.Armor pen means nothing to tanks.
3.You don't need armor pen to kill carries.
4.3.5/4 of ez abilities are ap.
5.ranked games, enemy players will have armor items decreasing the effectiveness of armor pen runes.
6.Many other guides show the difference in armor pen vs Straight flat damage rune, their conclusion is that armor pen is only slightly better late game for straight auto attack.
7.most ez players do not get 40% reduction in armor > useless runes.

Pros-Fast movement, good kiting, adequate damage, good surviability.
Cons- none really. you may not have "epic" damage, but if you attack them, they will die.

I will go over why I do this item order in following chapters.

Rune page-1. damage level runes + damage to q/r
2 .ap level runes damage to q/w/e/r
3. damage runes yellow ^^
4. mana regen- harass more and stay in lane longer
1. dorans blade- damge lifesteal +hp- best item you can buy/per gold
2.madreds - more detail later
3.sceptor- unlimited hp regen if played right.
4.boots
5.sheen- q proc
6.blood razor- armor bane
7.negtron x2 necissary Mr for surviability
8.swiftness-necissary movement gain
9.trinity-^ plus slow/ crit
10.fon-necissary movement/mr gain
11.veil- necissary cc reducer
12. gunblade- usualy never get- ^^ in damage and life gain / surviablity/ slow

Basically the extra armor from defense makes the difference between fb.
Extra damage from offense spec also makes the difference between being the one in charge in mid with your 2 offensive summoner spells.

1.Getting mystic shot first lets you early harrass
2.Getting blink next lets you place yourself in proper position to kill
3.Mystic shot again for greater harassing/killing power.
4.Essence to slow their attack speed and extra damage.
5.The damage from essence level 2 gives a much more wallop than a level 3 mystic for mana/ damage/ apm

The rest of skills are up to prefference of the user.
but it should be duely noted that adding skill points to blink is not as effectiv as other skill slots.

Exhaust and ignite perfect combo to be the one in charge in middle. If the other player ignorantly believes he is in charge middle and starts pushign your tower to hard you should effectively be able to kill him at this point by simply blinking past creeps and comboing him with all spells.
Since ezreal already has a flash installed, defensive summoner spells only take away from your offensive capabilities.

Using this item to its full capabilites is a must for this build.
Also, I found that combing the recipe of madreds into wriggles is a big no no. it takes 1000 away from blood razor build and doesn't give ezreal that much more potential.
A. he already has 15% proc, and 15 % lifesteal(total)
B. buy wrigglers = 20 % proc 21% lifesteal(total) 23 armor
C. The only reason you should buy wrigglers is if and only if the other team is Severly AD heavy > wrigglers early > then switch buy order trinity for bloodrazor,

1.Being able to finish off large creep waves fast while your playing defensive early game then readily using your 50% attack speed bonus to jump on the enemy pushing your tower.
2.getting early rune buffs for ganks
3. restoring hp after harassment
4.fast dragon

Essence flux is the perfect skill for pushing towers fast and easy, this may be one of the many reasons to level flux before blink.

With your rune page, you should be a force to be reconed with at level 5.
However in my opinion if the other play is being too aggresive around level 2 he is prob very killable.
with level 2 mystic shot level 2 essence and level 1 blink exhaust/ignite
At this point the enemy should either be low < 75% hp or dead already by your pownage of epic damage on q and some nice harrasing. If he hasn't died already soon as you proc level 6 , blink on his ***, exhuast/ignite>essence>mystic>R = death this trick must b learned to be even remotely good with ez. ***Even if they flash away**** the exhaust gives you perfect time to aim and shoot your R Without them moving to much.]

If you are still having problems powning at level 6/7/8 it is time to go back home buy your madreds/vamp and boots to stay competitive.

1.This is the point where watch sidelanes for gank opportunities, and prevent your laning partner from moving out of lane to gank your allies.

You make this possible by

A. madreds- killing creeps faster to make him stay and defend tower.
B. harassing
c. if you feel like you can, kill him if none are MIA!!!!!!!
You'll b ready to gank when

A.20 seconds left on your R and your ignite and exhuast refreshed
B.Middle tower is pushed and no one is home.
c. top or bot lanes are pushed.

Note:Your allies and you should be more than enough to kill one or 2 people without using ult.
however if your lacking confidence or your allies are lower than other team ^_^

Note: when ganking Use your ult after you gank a lane to cover mid tower from getting pushed.(if possible) Go back mid lane for a bit then wait for R to come back, buy and cover your lane rinse and repeat.

Note: if you believe they have warded top and bot lanes. take the sceneic route and blink over forest/ don't let them see you coming wait for e to come back, carefully aim your R >e>w>ignite don't use exhaust unless they charge you. This works even if they are on tower********)

At this point you should almost have bloodrazor/trinity, depending on other team composition.

Note:At this piont if they have any good ap carries they will start hitting VERY hard at this point regardless of how well you've been doing, unless its one of those rofl stomp games.

1. You have enough armor> from wriggles/bloodrazor, whichever route you took, and level by leveling.

Their team comp

A ap >=2 buy 2 negatrons**regardless if hes tank.
B. 4 strict ad, 1 ap 1 negatron, 1 chainmail

Also at this point in the game, those dirty tanks will have armor and hp to counter you and you will notice your damage is not scaling as well round level 18. Buying bloodrazor is a must to stay competitive with damage output on ad ezreal. Blood razor and trinity is all you need for damage.
At this point its up to good teamwork to finish up the game.

Use essence flux for fast pushes when you know other team is in bad position to cover towers (this requires wards).

1.Dorans
2.boots/vamp sceptor
3.madreds
4.wriggles
5.phage
6.trinity
7.boots of swiftness
8.negtronx2
9.bloodrazor
9.fon/veil


Some teams/ most teams are not well balanced with ad and ap, thus the extra armor bonus from wriggles isn't as effective as the bonus damage and lifesteal from gunblade.

Also you want to finish veil before trinity in some cases with heavy cc teams.