Pros:
LONG range (sniper shots)
Awesome Damage
Free Blink
AS buff/debuff
good synergy with AD
Benefits from AD AND AP

Cons:
SQUISHY
Vulnerable to CC
No CC (can compensate a bit with items)

WIP (work in progress)
by SPUDNUTS

Feel free to switch some runes around. Like siwthcing out MPen for CDR or whatever you feel is necessary. I like to run ArPen, since I don't buy any items for it. I'm going to try out more MPen, since it would benefit every skill but Q. You can throw in some AD instead for a small boost.

Armor runes are just to help survive, the flat armor really helps early game.
If you feel like you don't need them, get Mana Regen/sec, since you can always use more mana regen or something.

Also, Move Speed Quints would be nice to have instead of ArPen, but I prefer the extra damage.

Kinda self-explanatory. Adjust how you feel fit, I went for damage over anything else. You could put more into Utility and get longer neutral buffs and/or move speed. I think damage works best.

CORE: Rageblade, Trinity Force

Doran's Blade
Start with this. Lifesteal + AD + 100HP = great.

On your first stop back, grab either another Doran's Blade or Boots of Speed or both if you can.
Doran's if you need more damage/health
Boots if you need more speed
Preferably get both on your first trip back.
The double Doran's Blades help a lot with sustainability in your lane.

Finish your boots unless you really need the damage from Pickaxe. CDR boots are amazing, you can spam your ult all over the map. Bezerker's will work, it's more of an auto-attacking thing, which you should be more spamming your skills and staying as far as you can (since you're so squishy). Boots of Swiftness would work very well too as they will help with your kiting. Merc Treads if the other team has a lot of CC, but you should try to stay out of situations where you would need them.

Next get a Pickaxe or Blasting Wand. I prefer the Pickaxe for the extra AD, but if you find you're harassing more with Essence Flux / Arcane Shift / Trueshot Barrage, then get the Blasting Wand as it will benefit them more. If you're doing very well, grab the whole Rageblade.

The Rageblade is amazing on Ezreal. You get a good boost of AD, AP and you gain AS and AP as you attack, so when you're in the middle of a fight, all of your skills will do more damage (from the AP boost w/stacks) and you'll be Auto Attacking faster, doing more damage.

Next I like to grab a Phage for the extra health and slow chance, but you can swap this for a Sheen if you'd rather poke more with Mystic Shot.

Finish off your Trinity Force, buying whatever you can whenever you're at the shop.

I like to grab a Frozen Mallet next, to kite like a boss. Not to mention the extra health is ****ing amazing.

If your game is lasting this long, grab a Vamp Scepter if you need the sustainability or a BF Sword if you want the extra damage. Finish with a Blood Thirster.

The game is probably over by now, but if you're not dying much or taking too much damage, grab an Infinity Edge or even another Blood Thirster if you want.
But you may want a little more defense, and that's why you grab a Banshee's Veil. The Spell Shield is priceless, you get MR, Health, and Mana.

This is probably a little redundant, since I assume if you're reading this build you know how to play Ezreal.

(Passive) Gaining a 10% AS boost for each stack (max 5 stacks) is pretty handy. With Rageblade stacking too, you can fire off shots pretty ****ing quick.

(Q)Mystic Shot
Your primary attack skill. Great for harassing and poking enemies. It has a relatively low mana cost so use it when you can, but be sure to ALWAYS have enough mana forto get away from any situations that go bad. Max this when possible.

(W)Essence Flux
This is a great tool to debuff AD champs attacking you and help your teammates at the same time. Use it on any teammates nearby when taking down a tower, the passive stacks help. Useful for dragon/baron/towers/teamfights. It costs a decent chunk of mana, and does okay damage. Use it for that extra damage/passive stack while ganking. I like to level this up overfor the extra damage. Since this build has some AP from Rageblade and Trinity Force, it it does some decent damage.

(E)Arcane Shift
I primarily use this to either line up Mystic Shots, escaping from bad situations, or chasing down runners. The damage is okay IMO, it stacks well with AP, so any AP boost will help a lot. ALWAYS have enough mana to cast this so you can get away. You can use it to gain passive stacks, but I like to keep it open for a getaway tool.

(R)rueshot Barrage
Awesome for taking out runners. Using this to initiate teamfights is great. Since it does quite a bit of damage, it can demoralize the enemy, since some squishies might start to flee. Another use it clearing creep waves if needed. I find that if you use it on an enemy champ attacking an undefended tower, it can scare them away more often then not.

Good Choices:

Ghost
With the upgraded Ghost mastery, this is great for chasing down enemies, getting away from bad situations, or just getting places.

Exhaust
Upgraded exhaust mastery. This is used for ganking. Since you're most likely mid, this will help the other mid not get away from you.

Other choices:

Flash
You already have a built in Flash with, but a double teleport is an amazing get away tool.

Ignite
This is great for facing anyone with lifesteal/regen. See: fiddle, mundo, swain, etc

Anything else isn't worth getting as these choices are better over the others.

Grab mid if you can.

Just stay back, last hit minions with auto-attack. Try to useto only harass/poke enemy champs. Useto jump over creep waves or to the side to line up.

You should be doing fairly well in mid. I tend to have trouble with Swain (the large AOE stun followed by drain). Ignite works well here.

Cait is an annoyance sometimes due to her massive range (both distance and wide) on her skill shot. dodge side to side rather than back/forth.

Orianna can be a little tricky since she can stay far back behind minions and harass you with her ball. Just stay away from clusters of your minions so she doesn't damage all of you. Play defensively andwhenever you get an opening. If you have the mana, harass with, but it's costly and doesn't do great damage early on.

Buy wards if you have the extra gold and lane the side bushes. If you're low on gold and are worried about a gank, just buy 1 ward and put it on the side you think is most dangerous.

If you see a good chance to attack... Wait for all your cooldowns, thenas close as you can get (unless they're a very damaging melee or have skills that would make this a bad idea) andif there's no minions in the way > (Ghost if needed), Exhaust (for the slow mostly )>> auto attack untilhas great range, be sure to aim where they're going though. If you're post-level 6, and they get away, finish them off with( if their health is low enough ).

Grab any health potions if you're getting harassed a lot, but if you're taking that much damage, try to play more defensively.

Initiate with eitheror(or save Trueshot for picking runners off). Useon their melee or ranged AD (hit as many as you can). Savefor escape or chasing, or if you really need it, use it for passive/rageblade stacks.
whenever you can, then autoattack that **** til it's dead.

Always try to mid. You can harass like a boss.

Use

to hit enemy champs whenever possible (as long as your mana allows it)

Once you have your double Doran's Blades and Boots, you should try to grab blue if you can. This will help you spam your skills like no other. You won't have to worry about mana either. You should be able to useevery ~45s or so. Use it whenever you can, unless a teamfight is nearing, save it for that.
teammates when downing towers/inhibs, even if teammates aren't attacking it will give you passive stacks. Also use to harass when enemies think they're safe behind minions. Use when getting ganked by AD champs (Ashe, Xin, Yi, etc.)

ALWAYS have mana for, it's your only escape really.

Double Flash is awesome.

Ganking:>> Exhaust > [Ghost] >> AutoAttack w/when possible

Always try to keep your stacks up when fighting enemy champs, or even if you think you're about to be ganked.

Don't be afraid to grab health pots when you need them.