What is this!? -1

Cheatsheet
Scaling HP Runes? Please don't. You can start boots + 4 pots now, but I wouldn't recommend it. And Corki is like the worst ADC to try for an Elixer start. Maybe mention Doran's blade, since that's a really popular start right now? Never suggest Occult, or Guinsoos, not even as a joke. But I don't really think Elder LIzard Corki would be that troll. Frozen Heart shouldn't be part of a core for an ADC, but I can't speak for the rest of the items. You need to max 1 ability first, you can't jump between 2. Masteries look fine.

Main Guide
Your Runes and Masteries sections have flawed BB Coding (Broken Links). Try to fix that. Skill Sequence should probably be higher. Your Item section is a little questionable, but explanations make sense. I disagree with the item choices highly however. If you spam Phosphorus Bomb (as you recommend in your Skill usage), you go OOM super fast.

Counters
I honestly nearly stopped reading when you said Garen counters Corki. You should 100% never be in the same lane as Garen, and even if you were, you should do fine. Your Valkeryie gives you safety and you can easily kite and harass him. Viktor is questionable as well, his stun is far from instant, as is his main damage source (Death Ray), so you should be able to get away easily. When you said Zed is weak against Corki, but Talon was strong, I realized you clearly don't understand how they work (Zed is just a stronger version of Talon in damage output at all levels, and can't be zoned easily).

Overall
Most of it is hugely flawed, and lacks detail. -1.

For the love of all that is good, take your email off before it gets flooded with all manner of filth.

this

The guide was interesting till I read your counterpicks list. Thats complete ********.

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Wrong runes, skill order, short guide. -1