AP Ezreal is a really strong late game carry who excels at poking and bursting down non-tank targets while having good utility.
This guide suits my personal playstyle the most (Which is high risk high reward).
That's why I go maximum disrespect with runes/masteries/build.

So yeah my summoner name is Paddy Senpai. I'm playing on EUW.I used to be Diamond III in Season 3, Diamond V in Season 4 as well as Diamond III in Season 5.
I've been playing AP Ezreal ever since he's released and for me he's the most fun champion to play (Especially cause of that devastating global ultimate).

Many people complain about him but I personally think that he's actually viable even in high elo. Yeah there are quite a few "counters" that are currently pretty popular but the thing is if you play and practice him enough there are no real counters because there is always a playstyle that suits the situation (since he has a pretty high skillcap (in my opinion)).

Offensive = Red marked
Utility = Light green marked

For Runes I go maximum disrespect.

x3
Greater Mark of Hybrid Penetrationx9
x9
x9


Greater Quintessence of Ability Power because these are definitely the best for a good scaling AP carry (which AP Ezreal is).

Greater Mark of Hybrid Penetration because your early damage is a good mix between physical and magical damage. (early poke with Mystic Shot+aa's) (Getting ahead early -> snowballing -> reaching end game faster (in which AP Ezreal absolutely shines))

Greater Seal of Scaling Ability Power and Greater Glyph of Scaling Ability Power because it benefits his damage the most since he's at his best in end game.

Click HERE for a link to a screenshot of my masteries (directupload)

Just as for Runes and Masteries I also go maximum disrespect with Items. Like I said you don't need any defense.

Example Build

Let's get started

First up: always buy some Health Potion and Stealth Ward / Vision Ward If you've got some gold left

I start off with a Doran's Ring and Stealth Ward and 2x Health Potion.
The Doran's Ring allowes you to poke and get some mana back for cs'ing.
Stealth Ward to prevent early ganks.

Your absolute first item needs to be Sheen.
Sheen is really really strong on AP Ezreal early.
It gives you mana.
And it improves your poke / burst at pretty low cost.
Also you need it for Lich Bane so you need to get Sheen anyway.

Go for Ionian Boots of Lucidity for the cdr AND cdr on summoner spells (which is awesome)

At this stage of the game you can sell your Stealth Ward and buy either Sweeping Lens(to clean up some wards / counter against champions who can go invisible) or Scrying Orb(to prevent ambushes / get sight of enemies for countergank potential or to snipe someone with your Trueshot Barrage

Next item should be Morellonomicon. (Edit or Nashor's Tooth)
It's cheap for the 80 AP 20% CDR, Mana regeneration and (actually really good) side effect that it provides.
With either one of them we'll be able to reach 40% CDR.

(You can switch the order of the next two items you purchase depending on what you prefer(i personally prefer lichbane first over Rabadon's Deathcap except when you have 1250+ gold then go for Needlessly Large Rod first))
To even further improve that burst you need Rabadon's Deathcap.
Rabadon's Deathcap is EXTREMELY good with our build/runes/masteries since all we focus on is getting as much damage as possible.

Next up is getting that Sheen into a Lich Bane. (If you didn't already do this before)
Although Lich Bane's effect got nerfed It is still a huge damage improve on AP Ezreal. Definitely needed. (And it provides 10% CDR which is great for the loss of cdr we got through new masteries and changes to Ionian Boots of Lucidity

So what do we have ?
40% CDR and a really really good amount of burst.
The next item should be Void Staff. Never forget Void Staff It's ALWAYS needed no matter how the game goes.
After that you'll be able to 3 hit (e+w+q) anyone who hasn't bought much Health or much Magic resistance.

The last item is situational. You can go Zhonya's Hourglass for example to counter Zed or Karthus R. Hextech Gunblade is also viable. Same with Archangel's Staff.

Lvl 1 Mystic Shot since it's low mana cost and pretty decent damage.

Lvl 2 Arcane Shift because it's make you less vulnerable to early ganks + you can dodge spells more often.

Max out Essence Flux first because It is your main damage ability and it has no unit collision(So the poke's strong with this).

Max out Arcane Shift second because it increases your burst more than your Mystic Shot does. Also because it lowers your CD on Arcane Shift significantly (Which provides more mobility, utility and makes you less vulnerable to ganks/skillshots).

DON'T max out Mystic Shot first because that way you WILL DEFINITELY lack a HUGE amount of burst.
You'll just throw away kill potential. Bad Idea.
Some "pro-guides" may recommend maxing out Mystic Shot first for better pushing power. Yeah you are able to push better with Mystic Shot but like I said it won't make up for the huge loss of burst. Which ultimately results in losing kill potential and reaching endgame not as fast as with kill potential. Yeah that's my thoughts on it.

For Summoner Spells I go Flash / Ignite most of the time.
Flash is just OP. Always take Flash.

Ignite is the extra amount of damage that you need to get kills since it's not that easy to calculate your burst + Ignite damage as an enemy.

The only time I go Flash / Barrier is when someone counter picks me with a champ that has a huge amount of burst if you get caught (For example Annie).

Pros

- Good poke

- High burst damage

- Good utility

- High skillcap

- Good teamfight potential cause of huge AoE damage

- High reward

Cons

- No sustain

- No CC

- Not easy to master

- Easy to counter if not mastered

- Needs to have good positioning

- High risk

- Use your Mystic Shot to CS
- Don't hesitate to spam with your Mystic Shot since it costs barely any mana
- Mystic Shot is a good tool to reduce your CDs (including your Trueshot Barrage)
- Essence Flux is your main poke and damage ability in lane (use it when your enemy wants to get a last hit!)
- Don't use your Arcane Shift too much early in lane since it's mana cost and CD is high
- ALWAYS keep an eye on top and bot for potential kills with Trueshot Barrage
- Don't forget to get out of the enemies sight before using Trueshot Barrage to either farm mid or kill bot/top
- Keeping an eye on the enemy jungler can help you getting some easy kills + buffs ( Scrying Orb can help you a lot)
- You can jump over your Essence Flux with your Arcane Shift to gain the attack speed buff from your Essence Flux
- Don't hesitate to use your Trueshot Barrage to push mid/poke IF there is no potential kill on top/bot.

- When to pick AP Ezreal in ranked? When you've practiced him a lot AND if the enemy team didn't counter you already with for example Fizz or Syndra

- Let your team know which champions work well with AP Ezreal (for example Amumu, Leona, Malphite, Thresh, Blitzcrank). Basically anyone who can engage with a decent amount of CC.

- As I mentioned earlier positioning is really important in team fights since you have to line up your skill shots without getting caught by the enemy team (especially against assassins or AoE combos) If your positioning is bad for even just a moment then the enemy team can take advantage of that and bring you down since you have 0 defense.

- Your role in team fights is to shoot down everything from the distance (goes basically for every long range caster) If you get caught you will most likely end up dead since we go full damage.

- Never go all-in without having either Flash or your team to back you up immediately.

- Also never jump into the enemy team since that way you probably can't line up your skill shots properly anymore.

- You are the one who follows up. Not the one who engages a fight. Remember that (EXCEPT If you see an opening to take out the enemy AD or AP carry WITHOUT dying afterwards).

Team comps that work well with AP Ezreal

- Siege comps since Ezreal got an attack speed buff with Essence Flux + You can take down towers fairly quick with a lot of AP (Which increases the damage you deal to a tower with your auto attacks) and Lich Bane.

- AoE comps with a good amount of CC for example Amumu, Leona or Malphite because they will make it easy to line up your Trueshot Barrage and basically annihilate the enemy team (since Trueshot Barrage got a really high base damage (650) + a really good AP ratio (0.9).

- Poke/split push comps since AP Ezreal is (atleast in my opinion) one of the strongest poke champs late game (who can even take out enemies while poking if they make one single mistake)

Team comps who AP Ezreal is weak against

- Assassin comps with for example Zed, Kha'Zix, Akali. You will die a lot and probably lose the game if your team can't properly protect you.

- AoE comps with engages that are not easy to dodge for example Malphite, Amumu, Fiddlesticks (if he manages to land either his Terrify or his Reap on you immediately) or Veigar with his Event Horizon).

- Protect the ADC comps with for example Kayle, Janna, Lulu because they can easily counter engage when you try to burst the enemy AD or AP carry (Which will end up in you dying).

So overall AP Ezreal is (atleast in my opinion) a really good high poke high burst champ that has good utility with the runes/masteries/build provided above.

Again this is high risk high reward. If you manage to get ahead you will deal a HUGE amount of damage.
If you fall behind you'll probably be useless until late game.
Also AP is extremely good at snowballing.
Ask for early ganks -> snowball -> be huge.

The reason why i'm playing him as offensive as possible without any defense is the fact that he doesn't really need to "go in". You can always stay in the back and play defensive. That's the thing...Why would you need any armor or magic resistance? (except Zhonya's Hourglass for damage that you can't dodge) If you play him properly you won't receive any lethal damage. Going for magic resistance or armor is just a waste of stats and kill potential (which goes for ANY long range caster like Lux or Xerath).

I hope that I could help you improving your gameplay with AP Ezreal.
Feel free to give me some constructive criticism(Tips to improve the visuals of my guide are welcome aswell).
Also feel free to ask me anything anytime and/or add me ingame (Paddy Senpai | EUW)

Match history links (Match history links are with the old season 5 itembuild though)

http://matchhistory.euw.leagueoflegends.com/en/#match-details/EUW1/1744924004/343183

http://matchhistory.euw.leagueoflegends.com/en/#match-details/EUW1/1744838950/343183

http://matchhistory.euw.leagueoflegends.com/en/#match-details/EUW1/1741605546/343183

http://matchhistory.euw.leagueoflegends.com/en/#match-details/EUW1/1743149868/343183

http://matchhistory.euw.leagueoflegends.com/en/#match-details/EUW1/1738223225/343183

http://matchhistory.euw.leagueoflegends.com/en/#match-details/EUW1/1737190083/343183