Hi guys, I am Saipen and I bring to you a Guide of one of my favorite Champions Corki!
This is not that of a long Guide but everything I think is important is written down here. I think the best way to learn a champion is to play him and gain experience with him and this guide will only be a little help to find the right way! :)

I think Flash and Heal are really good on all ADC's its just overall the best and you can pick this every game. It provides a good escape in form of Flash in early parts of the game to get out of sticky situations just like ganks and in even in the late as you might think too it can really help you out. Heal gives you and your support a huge boost of sustain in an allin in lane and even in late you can overwhelm some opponents just like zed when he throws his ult on you and you just kill him cause you W away and heal when he fights you, most people just underestimate heal really hard in late.

You can also take Flash/Cleanse or Flash/Exhaust, both can be good too against some champion compositions but I really prefer to go Flash/Heal every game with all ADC's.

In my opinion the skill sequence shown above is the only one which is really viable on Corki, you still have this situational level 2-4 skill order where I normally go Q,W,E,Q and sometimes I skill Q,W than another Q for more poke in lane and then E again. You can even go Q and E second if your supports land a hook on your opponent level 2.

Skill Orders 1-4:

Standard: Q W E Q
More Poke: Q W Q E
Level 2 Allin: Q E W Q

The runes I chose for Corki are fairly standard for ADC's I mean you have 9x flat AD for general autoattack damage with also effects your AD scaling skills, you have 9x flat armor which I think is much better right now than health runes for general sustain in lane and you have 9x flat magic resist against all kinds of botlane supports cause most of them will do magic damage and also you got the 3x attackspeed quints cause Corki has this great passive which generates 10% of his flat ad as true damage on every autoattack which is really.
You can change like the quints into flat AD too or maybe lifesteal quints but I prefer to run attackspeed quints with Corki alot.

PROS

+ REALLY STRONG LANING + INSANE POKE WITH ULT + ONE OF THE BEST ESCAPES + SKILLS DOES MAGIC DAMAGE + GREAT SPLASH DAMAGE + EVEN STRONG IN LATEGAME + BEST ADC FOR SOLOQ + VERY STRONG MIDGAME

CONS

- REALLY MANA HUNGRY - USELESS IN MID WITHOUT TRINITY

Must have Item on Corki! Without it you do not do any damage in mid game.

These are so much better than Berserker's Greaves cause Corki does magic damage with his AD scaling spells.

I normally go Botrk with Corki after my Trinity cause it is just such a good item which gives you sustain and you can only benefit from its passive when your opponents have someone with really much health.

I go this item instead of Botrk when they have a squishy team, you dont really need the attackspeed on corki and 10% extra lifesteal are just nice. And then there is the fact that Corki's skills scale with AD so you will benefit from the flat AD.

I think you CAN go this item on Corki but even most pro players just skip this item. The thing is that you do enough magic damage through your skills that you dont need any AD penetration. Beside that your passive does true damage and your E is an armor shreed so you really dont need it unless your enemy's team have like Sion Top, Rammus Jungle and Thresh support and all went full tank or something like that.

This item is my favorite replacement for Last Whisper. I first saw this on Doublelifts stream and I tried it by myself. Against an normal not heavy tank team composition it feels much more effective compared to the Last Whisper and it just synergises much more with Corki cause Corki's E and passive already provide a lot of "armor penetration".

I never go this item directly after Trinity Force! I always get sustain first. You dont really need the massive damage from an Infinity Edge with Corki cause you not even build him on crit chance, sustain is there much more worth but after getting a Botrk or an Bloodthirster this item provides a massive damage output and really synergises well with your overall damage.

Go this against heavy Assassin teams where everybody wants to oneshot you. This item will make them think: hmm if I jump in and kill him he is not really dead so its not worth it if I die.

This item is much better if they have high amounts of cc instead of raw damage. Chose this if there is like a Lissandra or a Blitzcrank and so on in there team and you feel that you cant dodge all of there CC.

I think farming with Corki is very easy cause he have really good wave clear.
If you see a really big wave just Q on top of it and follow up with your ultimate, you most likely will clear the entire wave with this little combo and are much richer then.

As I said, this is not that of a long guide but even then, thanks for reading it and I hope that you will play Corki and dominate your games :)