This is my first build so bear with me. I was originally drawn to Corki because I was told by a friend that he was a horrible champion and by nature I had to prove him wrong. I feel like Corki can really be a hit or miss champion and he's definitely not the best ADC out there but if played right he can do massive damage.

I pretty much go for the cookie cutter build here on runes. Corki should be built with lots of armor penetration for most effectiveness. I'll post screen shots later of some end game crits ranging over 1200.

Again here pretty much cookie cutter stuff. Max offense, upgrade summoner spells, and rest to defense.

I love this item build for Corki! It incorporates all the things required to melt champions. High damage, lots of crit, and tons of armor pen (plus a little life steal to increase survivability). I recently added ghostblade into the end of my build after realizing how perfect it fit in. It's a well rounded item perfect for most adc's. Stats are as follows: 30 AD, 10 CD, 15 Crit, 20 armor pen, and an active that gives 20% movement speed and 40% attack speed for 4 seconds. The active on ghostblade is 45 seconds which almost ensures it's up for every fight making it a beastly item. Did I mention I like the ghostblade?

Phosphorus bomb to me is only good for revealing units in the bush or fog of war. It has a high mana cost and doesn't have the range of a good poke. That's why I level it last. On the other hand if used efficiently it can really help in the laning phase. I prefer gatling gun as my go to ability for farming and it's Corki's most useful spell in team fights and it scales with AD. Use Corki's ultimate to poke before engaging and to punish enemies who chase you. His Gatling gun is Corki's bread and butter. It's not only a tool for farming creep waves but it's armor shredding effect melts every champion exposing them to huge damage from not only basic attacks but Corki's passive as well. This ability has an aoe effect and like the black cleaver it benefits the whole team in fights. Valkyrie is a boss move but with such a long cool down plan your use accordingly as it can make or break you in a fight. Ah and Corki's ultimate... it may be one of the best pokes in the game. Once at max stacks you can rapid fire missiles with every 3rd missile doing increased damage. Great for pokes, finishing blows, clearing creeps, and punishing chasers. You can even launch missles into the bush to look for hidden champions.

I'll come back to edit this thread later after I receive feed back and capture some screen shots. Please feel free to comment and let me know how you feel about this build.