This build is made for an early aggressive play on midlane and a useful teamfight opener at late-mid and endgame.

Please excuse my english. English is not my native language, but at least i will try my best ; )
The layout and style will be changed in the next few days.
Also i will add the same guide in german. Of course with some more details and facts how to play and win.

Magic penetration runes in combination with the "Sorcerer's shoes" are very useful for a hard harrasament at the early game.
Of course you could take the "Ionian Boots of Lucidity" for cooldown reduction, but there for i recommend the "Morello's Evil Tome".
I choose armor per level runes Greater Seal of Defense because they are useful against an ad carry on midlane and because of the low life at the endgame, where a little bit armor could save your life.
With cooldown per level runes i come to cooldown cap at level 18 in combination with "Morello's Evil Tome" - unbeatable!
At least i take 3 runes of "Greater Quintessence of Swiftness" because even with boots Orianna is a very slow character. And what is more important than to be fast?

Well, i think the masteries speak for themselves. 23 points into "Utility" and the rest for some ability power and cooldown reduction into "Offense".
Thanks to the Utility and Offense masteries you will have enough mana and cooldown reduction for fast and continuing harrasment.

On midlane it is important to stay as long as possible against your enemy. There for i choose the "Meki Pendant" for mana and 2 health pots.
First go back to base when you are able to buy "Boots of Speed" and maybe even "Amplifying Tome" .
With finishing midlane you should have got the "Sorcerer's shoes" and "Morello's Evil Tome" . At the best you have got the "Blasting Wand" for "Rabadon's Deathcap" bought.
All other item will follow in the mid- and endgame.

The skill sequence is very simple. There are just a few cases where you should skill "Protect" earlier. For example against an enemy like "Nidalee" whose able to throw her annoying spear.
Of course "Shockwave" has to be skilled as early as possible!

Well, i think i do not have to say a lot to the summoner spells. Use "ignite" to kill. Use "flash" to flee or to kill as well.
Every other summoner spell does not bring the effectiveness like "ignite" and "flash" in combination. But try it on your own, you will see it.

Okay, a short summary.

Play aggressive and use your cooldown reduction for an early harrasment. Take care for your mana, Orianna needs a lot. In Teamfights you should wait for a good moment, where all enemies stand near by each other and throw your ball in combination with "Shockwave" - a great opening.

More details later.

With Orianna and specially this build you should not go jungling!

A very important theme! Orianna is born for teamfights and teamsupport.

Opening

Wait for a good moment, where many enemies stand near by each other, to get them all and throw your ball, use "Shwockwave" and "Dissonance".

Support

Choose "Protect" to save your teammates or to start an engage.

Chase

In case of a chase give your teammate, whose near on the enemy "Protect" and use "Dissonance" for speed. Then you can also use "Shockwave".

Do not use too much mana against creeps, specially not in the early game. Orianna eats mana like little children chocolate. Anyway in the mid- and endgame there is no problem to throw your ball and use "Dissonance". With enough ability power no creep can resist this combination.

Pros:

- high cooldown reduction
- high movement
- high damage
- great support and carry

Cons:

- early- and early midgame low life
- early - midgame low mana