This is a build that focuses the innate properties of Ezreal and his Mystic Shot (Q), his high level of mobility, and his prowess for making good escapes. Ezreal is a very squishy champion as everyone probably knows, but he has a very high damage output if positioned correctly.

The guide was written with the purpose of being easy to follow for less experienced players. I avoid playing number games and lots of math. I just tell it like it is. I also did it because I love this champion. People talk alot of smack about he has been nerfed, and that is true. However he is far from useless.

The three most important aspects of this build:

1. Strong early laning phase. This is done through excellent mana regen, armor pen, and focusing the squishy enemy champs. This build is designed be highly mobile while spamming Q to last hit minions and harass low-armor enemy champs (think Ashe, Twisted Fate, Akali, etc)

2. Building a steady stream of armor penetration/damage items. As champs level, they gain armor naturally. Our item set is going to negate that bonus as both teams level. Obviously it is less effective against tanky fellows. You will be doing 1/5 to 1/4 their health in damage to squishy carries (per mystic shot). You will do it in style and without ever getting into their attack range.

3. Realizing that you cannot take damage. You just can't. You will utilize your high range and spamability to hide behind the stronger members of your team to dish out damage.

PROS
FUN, mobile, anti-carry, relatively simple to learn, really allows for more creativity in your attack/harass/escape strategy

CONS
squishy, not good against tanks, gets killed by stunlocks/snares, useless if early game fails.

The aim of this mastery and rune build is to keep you in the lane for as long as possible. I always felt that it is best to spec your builds for early game (if your early game goes well, then late game will too).

14 points in offense to gain armor penetration and cooldown reduction.
16 points in utility to gain increased mana regen, increased buff duration, and improved flash.

As previously stated, early game is everything. Your armor pen runes are going to be the basis for a very strong offense, while mana regen runes (combined with early game Meki Pendent) are going to allow you to repeatedly spam Mystic Shot and sustain your damage output.

Teleport - what can be said? My strategy is to save teleport until I have enough gold to buy boots 1 and Brutalizer (350 + 1337). Port home, buy that stuff, and port back.

Flash is reserved first as an escape tool, and second as a chasing tool. Combined with arcane shift, you can jump multiple walls, or just jump really far down the road. If you're trying to escape, use Arcane shift, then Flash. No need to use Flash unless absolutely necessary.

Passive: RISING SPELL FORCE
Basically, any time one of your abilities hits a champion or minion your attack speed is going to be increased slightly for a few moments. It stacks up to five times. It's not significant early on but it may come in handy if you can use your ultimate to max it out during a team fight.

MYSTIC SHOT
This shot is your mainstay. It's a long range spell that travels at high speed and deals physical damage. The amount of damage is a flat-rate + your physical attack damage. The best part about this ability is that if it connects with an enemy, it will apply on-hit effects: things like lifesteal from a vampiric scepter, frost from a frozen mallet, or armor penetration from a last whisper. We're going to take advantage of this. It has high damage and low mana cost.

Mystic Shot also reduces Ezreal's cooldowns by 1 second if it hits. Basically if you hit, you can cast it again almost immediately (at later levels). This is just another reason why your damage is so high.

ESSENCE FLUX
This is a secondary spell for this build. You won't be using it much to do damage, but rather to support your team or harass your enemy. Every ally that is hit by the shot gains bonus attack speed, and every enemy that is hit is damaged and loses some attack speed (temporarily). Since we're not going Ability Power in this build, it won't do much damage. It is still useful for reducing enemy farm and if you cast it on your team while they attack a tower, they will likely destroy that tower. Also it can be used in conjunction with the other abilities if you need a little extra damage in your burst.

ARCANE SHIFT
Ezreal's second most useful spell. Ezreal will blink to a nearby location and fire a homing shot at the closest enemy. It's basically Flash with an attack stuck to the end of it. Naturally, it owns. It costs very high mana so you should save this for escaping or chasing. It will do decent damage at level 5 even though we're not using ability power to boost it. You can use it for easy kills on escaping enemies since it is impossible to miss or for *cough* stealing kills *end cough.*

TRUESHOT BARRAGE
This is a global skillshot (think like Ashe's Crystal Arrow). It passes through every enemy it touches, dealing damage (based on AP) and doing less damage for each person it touches. It has decent damage early game, but late game it won't do much against tankier heroes. It's going to be your move that says "Hey *****es. I'm here. Now...come at me bro." Cast this to hit as many champs as possible during a team fight to quickly build up your passive. It can also be used to snipe escaping champions with low health...although it is kind of difficult to hit with across the map.

Phreak's champion spotlight provides a good explanation. Though dated, the principle still applies. LAST HIT MINIONS. I'll recap for those who haven't seen the champion spotlight.

Using your meki and later your boots, you just need to position yourself so that your Mystic Shot last hits minions. Wait until a minion is at about 1/5 health, maybe less depending on minion level, and you'll be able to last hit with Mystic Shot. You can also auto attack a minion until it is low health and immediately Mystic Shot it to kill it quickly before friendly minions do.

A secondary use of teleport is to move quickly to other lanes and farm large creep waves. Make sure you practice good map awareness in this situation. Don't get ganked.

Start with Meki Pendant and 2 health potions. This one meki pendent is all the mana regen you're going to need. You're even going to sell it off later.

Boots of mobility are mainly for getting you to the action faster if teleport is not ready. They also come in handy for escapes. Since taking damage in any form is considered "being in combat" your boots will not give the speed boost you need - this is why you have Flash and Arcane shift. Get away from the damage source, and sprint away.

Brutalizer, Last Whisper, and Black cleaver (purchased in that order) are going to be your armor penetration/damage. Brutalizer affords a little bit of cool down reduction, but it's not significant. All of the effects of these items are attached to each Q spell you throw.
Somewhere between BF Sword and Dagger (For black cleaver), you can sell you Meki Pendant. Your base mana regen is high enough that you no longer need it.

Triforce - if the game has lasted this long (it usually doesn't) start working on Triforce. Begin with sheen, then move to zeal if you're doing very well K/Dwise, or phage if you need a little more health. Sheen's effects are also attached to mystic shot.

Bloodthirster - if your game is really dragging out, get a blood thirster. Chances are you have a lot of gold to spend. I recommend this item for its life steal component (works with mystic shot) and the possibility of gaining 100 damage from it. I've never had a game last long enough to get this, but it will allow you to defend well without having to retreat. Simply fire Q spells into an enemy crowd to regain large portions of health.

SIDE NOTE- DO NOT BUY INFINITY EDGE OR ANY CRIT ITEMS WHEN FOLLOWING THIS BUILD. MYSTIC SHOT DOES NOT CRIT. EVEN AT 100% CRIT CHANCE.