Allow me to explain in short what this build is.

-It's a PURE AD(Attack Damage) build for Ezreal
-It allows for skillshot spamming
-It allows for nuke
-It also grants a large mana pool which will also convert into AD

-It's very flexible

Depending on what you prefer, the rune build is as follows:

Red: Greater Mark of Desolation x9 (Armor pen)
Yellow: Greater Seal of Resilence x9 (Armor)
Blue: Either Greater Glyph of Warding x9 (Magic Resistance) or Greater Glyph of Replenishment x9 (Mana Regen).

Quint: Greater Quintessence of Desolation x3 (Armor Pen)

This rune build is simple. Armor penetration which is awesome for Ezreal throughout the game, Armor for a bit of defence and the choice of more defence (my personal choice) or more mana regen if you feel you need it.

The masteries as shown above basically offer more Armor Penetration, Damage, Magic pen (for his other 3 spells, particularly his ultimate, although it scales with AD the damage source is magic).

There is then more Mana regen offered, as well as a bit of cool down reduction.

Why have I not gone for a defense masteries? The plan with this build is too do massive bursts of damage at range, without taking too much damage. I'll explain in more detail later in the guide.

Starting with Meki Pendant and 1xHealth pot 1xMana pot is great for both laning and mid. It allows for harass and farm without costing too much mana. It's also great for getting your passive up if you're going in for a kill. Otherwise, don't bother trying to build up stacks of your passive.

Follow the build (rushing Tears of the Goddess), and focus on spamming as much as you can to farm minions, harass with auto attack or Q, and once your mana pool is on it's way to becoming significant (especially if you have Sheen), you can build into a Manumune, and probably jump up about 50-70 AD, with a mana pool that will allow you to spam.

Rushing a trinity force next is essential, and soon after that a black cleaver. From here you can either go for an Infinity's Edge, a Bloodthirster, or even a Madreds if their team is tanky.

They're going to hide behind minions, your job is to last hit the minions in between you and your enemy, and deal some damage to them.

If you find yourself dominated in lane (you'll find this against Brand in my experience), focus on using your Q to stay out of range, but be able to last hit. That's the beauty of Ezreal. His Q also applies hit-effects, so grabbing Red as much as possible will give your Q a slow effect, and trust me. This is awesome if they're just out of range of your auto-attack.

Don't bother getting your W ability until the guide says, as you're building pure AD. Your W ability will be ****, and buffing your team-mates with a measly amount of attack speed at the start probably isn't worth it. Especially if you're mid and alone.

As for your ultimate, it's damage is reduced by 10% for each target it hits. Try and use your teleport to get a clear angle of your target, but out of the way of other enemies, minions especially.

And that's all really. Spam, harrass, but remember. This build is squishy, but painful. It's your job to deal damage at range, and run away whenever they try and come at you, but go back for more. It can provide hilarious results, I've had some delicious scores with this build.

If you see me on US servers, I'm Sargath. I'm called Zepthos on EU, but on everything else, you can call me Kromus!

Hope this guide helps, it certainly works for me!
Cheers!

Kromus/Zepthos/Sargath