Not Updated For Current Season
The masteries shown here are not yet updated for the current season, the guide author needs to set up the new masteries. As such, they will be different than the masteries you see in-game.
This is my guide for Corki - the daring bombardier, and as you can see this is an AD build which in my opinion is the best way to build Corki.
There are 3 main reasons for this. His passive,, scales off his AD. His E spell,, lower the enemies armor, letting him do more damage with his auto attacks, but doing nothing to augment his spells. The final reason why I believe that an AP Corki is unfeasible is that his AP scaling ratios are horrible, the best you will see is with his,, which is .5 damage for every 1 point in AP, which isn't a lot.
Now on to the meat and potatoes of the build. Useto check the bush and harass dps champs,as it lower their hit rate TO 35%, which a lot of players don't realize, so use it whenever a dps carry gets close.
Useto escape ganks and jump over walls to set up ganks of your own,never use it to close with an enemy champ unless you know you wont have to escape quickly as Corki is pretty slow and very squishy.
Useat the start of any gank or team fight as it makes tanks squishy and squishies dead. Don't use it to farm because you always want it up to use on a champ and the few seconds that its on cooldown can mean the difference between life and death.
Finally we get to his ultimate,, low cooldown and mana cost make this a spammable ability, so use it to farm and make sure you always go into a team fight with a big one ready.