so, Corki, and pain to play and a pain to play against, some of the greatest poke in the game, and then just walks up to you JUST to proc a triforce, aaaaaaand your dead, corki is rather a fun champion to play mostly though, good escape, good poke as i said and a great tank shredder so really useful in a team fight.

now on runes you dont have to worry too much, as long as you have the damage and life steal play to what you wanna do, im not gonna force it down your throat (*GET THE HECK IN THAT STOMACH*) ahem...

now, attack damage is needed as well, your and AD Carry, why wouldnt you want it

life steal, just because you need sustain, it helps early game so you wont get murdered so easily

now with the mana regen and the cool down, i do it to spam rockets which is corki's main feature, it lets him play as him and lets you stay there instead of relying on a soraka or your fountain for mp

masteries, what am i to say, your there to deal damage, maybe take a little but not a lot and get out, all your there for, you can possibly change the defence masteries for utility if you wanna move around but thats up to you

items, its basically a shove off build, i have rockets, and your gonna get one in the face if you dont get away from tower, simple as that, high damage, its all about corki's ult, have fun with the big one, that one HURTS

the minigun just because it shreds SO much especially when you get black cleaver, this makes it so you deal damage in as much time as possible

Flash - why, cos screw you thats why, flash is the all purpose standard spell when you hit 12, dont have it, what the heck are you doing?

barrier - lets you survive, good health when you need it and lower cool down than heal

GOOD -
POKE IS AWESOME
good mobility
good damage

Bad-
passive doesnt scale with critical hits
rather squishy
long ability cd

SPAM ROCKETS WHEN HIT 6

but before that you may as well play safe and just try to last hit without using the abilities, save em for a trade as they do have a larger cooldown than other adc abilities

get in there while firing rockets and press e and watch em die, pretty much what you do, let people initiate, when they have, go in, if getting chased, w away and you should be fine, if not, JUKE OVER A WALL