Wild Card Ezreal
I love playing Ezreal as well as about half the LOL population XD

But with Season 3 I wanted to look at a number of things and started to develop Ezreal’s R&M (Runes and Masteries) and builds so that I could play Ezreal in 1 of 5 positions. I play Ezreal Top, Jungle, Mid, ADC, or Support and this guide will show you one of them.

But Why? Why learn Ezreal to play in every position? This is why. If you look at my guide “Phases of Summoner’s Rift” you will see a section that describes the priorities and things to keep in mind throughout the entire game, including Champion Select. This Wildcard Ezreal is for The Champion Select Phase:

First!: WildCard Ezreal is designed for 5v5 premade games.

First-pick Ezreal, this should bait out a counterpick for ADC (Example: Graves), but now your team gets to counterpick Graves. The enemy team is confused, they either assume a kill lane or that Ezreal is going Mid, so they counter Ezreal Mid (Example: Ahri), and now you get to counter pick Ahri. Continue this until each lane has an advantage and put your Wild Card Ezreal where ever the gods have placed him.

:) Enjoy.

Support Ezreal is my favorite surprise in this "WildCard" series.
I take advantage of the "Pick Pocket" Mastery and Ezreal's Mystic Shot to gain a gold advantage over my opposing support while encouraging long range harrass and zoning for my ADC to farm. My build is centered around a support's build getting GP5 items to start, sight stone for wards and Emblem of Valor to help my ADC.
maybe my biggest problem is that I call him "support" when really that's not what he is, the build turns him more into a kind of artillary. If you can free your mind from what your thought are of a support then new ideas can fill the space, like having the long range artillary support of an Ezreal who is pounding out aura's, damage, and all the while taking a number of heavy hits. I like my Ezreal support because I feel that no item is wasted. And when Ezreal is on a team with champions like xin, fizz, or any other auto attack favored champions, its AMAZING how that AS buff DOES play in.
What I like the most about playing Ezreal Support (Artillary) is that there is a heavy amount of damage output within your lane. Your Essence Flux allows ur ADC to build damage first (more on that later). Having that been said, this lane (kill lane) can be played both passively and aggressively, and that's my favorite part. the point is to farm up your Q/pick pocket and be ready to lay on twice as much damage if the enemy engages on you! :D

I take Mystic Shot as my level 1 ability, allowing me to immediately start harassing and gaining gold from my Pick-Pocket Mastery. For safety AND aggression, I take Arcane Shift at level 2. At level 3 I begin leveling Essence Flux and max it immediately after. While I may have more damage output by maxing Mystic Shot, I only level it to provide me poke (and income). By maxing Essence Flux I can encourage my ADC to purchase damage before attack speed. (It would be worthwhile actually to tell your ADC to focus on damage, often I play with ADC who rush Attack Speed items but you lane will already have an advantage in attack speed, making this basic attack hit harder is totally worth it.)
I max TrueShot Barrage whenever I can, and unlike an ADC Ezreal I look for openings to use the skill in the beginning or middle of a teamfight. I don't want to steal any kills or even wait to pick up trailing enemies. While the damage is not amazing damage, catching a moment when you can hit every enemy with it can give your teammates the advantage at the start of a fight.

Support Ezreal should absolutely take advantage of anytime his ADC recalls. His high distance will allow him to take a bit of CS that would otherwise, profit no one. Doing this, easily, without having to take damage (like a leona, or alistar would) can continue to help put Support Ezreal far ahead of his opposing support.

Support Ezreal has a really interesting build.
For the Laning Phase I build Support Ezreal to make like a passive support. I focus on ward coverage and sustainability so that my ADC and I can level faster and gain better income. I like this because the passive build combined with the very offensive playstyle allows ME to control the lane. I can push and take some small hits, but then I can sit back and wait to regenerate my health and mana.
As the game moves more into the Objective Phase I develop my builds into more aggressive, bruiser-like items, letting me tank damage and lay down some hits on the enemy team.
Because of this transition I like to build my Philo Stone into Eleisa's Miracle instead of building into a Shurelya's Reverie. While the movement speed could be favored by the team, selfishly, Ezreal doesn't need it and the item slot, i felt, could be used to better develop his bruiser capabilities. I try to wait until level 15 before getting Eleisa's Miracle but, be realistic about the money you have and what level you are. You may need to get it at level 13 or 14, just to ensure that you gain its 3-levels passive (when you consume the item but maintain its buffs for the rest of the game).