Hi. this is the first build i write down. i played orianna very much and this build really worked out for me, specially if the game gets old.
The reason why i write it down is because "thinks-he-knows-anything-but-doesnt-have-a-clue-" Scoolvac, who never played orianna tells me my builds just worthless ****.
bah im in rage. So you decide..
I wont tell anyone how to play orianna, this is just what u do special when u play like me :)

My choice of Summoner Spells, Masteries and Runes is connected to how u play Orianna in earlygame, and how u defend urself in midgame.
i choose Clarity because if u move ur ball a lot u can harras pretty fine and get creepkills as sideeffect.
The only thing i insist on with runes, are the spped ones. After you buy defence items quite late in game u survive by comand protect and speed. This is also why u buy boots of swiftness.

U should go mid. Orianna can be strong there, and you are kind of carry. good ganker also, specially after you are going to be pretty fast.
buy Meki pendant and healing potions.
with clarity and Meki pendant u will be able to move ur ball alot to harras and farm.
The skill sequence is about farming. u should soon be able to kill creepgroups alone by comand attack and disonance. dont forget ur near jungle if u got no jungler in team.
as sonn if you are that far, go for comand protect.

Play passive, here. you dont need kills to become strong, and you are really squichy

mid game beginns as soon as u start buying ap items.
in mid game You do two things: farm and support.
be carefull dont go for every kill, you have to avoid being focused by standing behind and go back fast after sending your ball. Support is what you focus on. You will get enough money by farming anyway

the rest of the game beginns as soon as you buyed Lich bane. This isnt really after mid game, because if you do your farming rgíght you will reach this point pretty early :)
Lich Bane is just perfect here. u get more speed, and some other defence also, so you can start going nearer to your enemys, doing a lot of dmg, throu the obvious combination of spelling and attacking.
(by the way u will be pretty good in 1 on 1)
With that you can kill a lot, farm a lot..
and you are still good for support..

rest of the items are about defending(which gets important after u kill a lot), and enabling you to do what u do faster.
variate your last 2 items, sometimes it can even be good to buy whits end.

another "by the way": In the end u are stilll capeable for BD, cause u are fast and hit towers pretty hard trough autoattack and Lich Bane.

This build isnt easy to play, you got to use ur speed advantage right. That and farming is probably most important. If you do it right, i asure you to have a lot fun with this build :D

im not so much in rage, now after writing. but still: Tell us ;)

greetings
von und zu Stein