Hello ladies and gentlemen.We can express our opinion here about corki free.I think now he became very awesome champ for skilled players who know how to use him.Also we can discuss the best build.I think for the beginning you should pick a doran's blade,if you don't make dmg pick second.You should start with ad runes and armor penetration.For boots i pick those with attack speed + enchant movement 2.If you are pro in the beggining and you get too much gold you should buy an infinity edge(it is very effective with corki).You may buy phantom dancer for attack speed,movement,and critical but I don't suggest it(It's better to buy a second infinity edge than waste gold for phantom).Depending on circumentances always you should form the build.For example if you have a strong tank for rival pick last whisper.Then a best choise is the bloodthirster.I usually pick one or two depending on the circumentances.Also beacause corki doesn't deal only physical dmg but also ap a hexteck would be fine(I haven't tested till now).