My first guild ever, I just had a nice match with this build, so happy so that so im sharing it with you guys. I've been playing Corki for only around 5 days and I've tried several other builds but I highly recommend people to try this, I've seen all those armor penetration builds that seem all bleh but just give this one a shot.

Pros
-Easy get away/chase
-Loaded with HP atk speed and life steal
-Gatling scares off everybody
-Phosphorus bomb reveals enemies in grass, AoE circle doesnt even have to be exactly on the grass but at least touch it with the sides
-Can Valkyry over walls for escape or to chase

Cons
-Fear stuns or anything that holds you in place

This build that I have came up with is designed to make your Corki the meanest and most BA Corki ever. Build big with some fiesty attack speed, damage and life steal, and also built tough with a Frozen Mallet.

First start off with the Doran's blade, this should give you enough health to survive alone in a lane and a bit lifesteal and damage to harass along with it. After getting a few gold, go ahead and work on those Bezerker boots for that 25% attack speed. Soon after, start building for a Phage, this gives you some nice HP, not too much not too little but just enough, some damage and a chance to slow, now your enemy should start to lose hope. Instead of building all the way to the frozen mallet, get the Sword of the Occult then the frozen mallet if you feel like you're on top of the world, indestructible. After the Sword of the Occult, head on to the Sword of the Divine, this should give you enough attack speed to scare off people thinking that they can kill you. The reason why I chose to get the Vampiric Scepter before Ghostblade is just to tag along with the Sword of the Divine as well as to help with the BloodThirster, atk speed + Life steal = win. When you think you have enough money, get the ghost blade, now you should be an ultimate pushing machine that no one can touch. Finally get the BloodThirster, fly around the entire map and kill everything until you get 10% bonus life steal.

Tips

-Before heading into someone to attack if your in a bush, shoot your ult then swoop in with Valkyry, charge up that gatling then ghost blade and fire away~

-If your teammates call MIA, don't get too scared, just stay and attack minions while next to a wall you can Valkyry over for a sweet escape.

-Don't be afraid to use Valkyry into an enemy attacking your partners, gatling gun to scare them away.

-If playing 3v3, after healing or spawning, use Valkyry to fly off the wall next to the Nexus to save some time if you're heading top.

-If you don't feel like you're on top of the world, get a phantom dancer instead.

-With Frozen Mallet and Youguu's Ghost Blade, activate the Ghost Blade and start chasing, the mallet should slow and the Ghost Blade's effect should stack, making kills easy.

Use Gatling Gun to spray while you fire at the minions in the back with your regular attack so that the Gatling Gun and hit all 6 at a time if you angle it right, just don't spam gatling too much because it'd burn your mana then you can't Valkyry away if you're about to get ganked.

It's only been 5 day's and it has come to my attention that there seems to be nothing wrong with this rune build, the armor pen just adds to your regular attack, that along with gatling gun should leave the enemy armorless, can possibly make tanks squishy as well. The attack speed runes is just to allow you to shoot a bit faster for a faster drop in armor equaling more total DPS.

The reason for Heal and Clarity is because when enemies attack you while your low, they should remain hitting you in your Gatling Gun's range, after you heal, they're armor should be low enough for you to take them out or flee. Clarity is to replace the ammount of mana you burn from abilities and can save your life if you're about to get ganked and cannot Valkyry into a wall because you were out of mana.

While laning with your team, stick with the person with a stun, snare or anything else that keeps an enemy standing still. Charge up that Gatling and fire away, spam rockets while your at it or just use regular attacks with ghost blade or both. This should do insane damage and should most of the time get you a kill.