Update June 5, 2011: Used advice from CrusaderMercutio and Jedzc and changed item build. See section Items for changes.

Update June 9, 2011: Added more insight and detail on summoner spells for Orianna. See section Summoner Spells for changes I am also considering changing the build order from
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to either
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or
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If you have any ideas on that, please leave a comment below. Thank You!

Update June 10, 2011: Changed build order to
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There once was a Piltovian man named Corin Reveck who had a daughter named Orianna, whom he loved more than anything else in the world. Though Orianna had incredible talent for dancing, she was deeply fascinated by the champions of the League of Legends. This fascination compelled her to begin training to become such a champion. It is unfortunate that her sheltered, wide-eyed naivete led her to take unnecessary and dangerous chances which ultimately led to her tragic demise. Orianna's death shattered Corin, driving him into deep depression and an obsession with techmaturgy. He could not stand the void his daughter's death left in his life, so he decided to build a replacement - one that would complete Orianna's dream of joining the League. What was created is the clockwork killing machine that Corin named after his daughter. Knowing that she was destined to be a champion and seeing the way the times were changing, he created The Ball as her pet and protector. This nearly symbiotic creation uses a different type of techmaturgy, relying more heavily on electricity than clockwork.

Orianna and The Ball now fight as Champions in the League of Legends, using her sometimes misguided morality as a compass. She tries in earnest to fit in with those around her. However, no matter how hard she tries, Orianna can never be human and there is always something unnerving and alien about her. Though she attempts social interaction with other champions in the League of Legends, there are few who can get past her exotic nature. To many, it's as if there's nothing inside, that Orianna is just a soulless clockwork shell - a dangerous and deadly one at that. However, all along she remains the perfect daughter in her father's eyes.

''Dance with me, my pet. Dance with me into oblivion.''

Here is the Champion Spotlight hosted by Phreak. Watch it if you think you want to learn more about Orianna after reading my guide or just watch it for your own entertainment. Enjoy ;)
Play Video

I recently found Colbycheeze's video guide on youtube and found it somewhat similar to the way I enjoy playing Orianna so enjoy ;)
Play Video

Playing As: Orianna

* Command: Protect can be used on yourself to return the ball back to you quickly. Combine this with Command: Attack for a quick harassment.
* Command: Dissonance is a very powerful escape tool if Orianna has the ball. The combination of speed and leaving a slowing obstacle can be quite powerful.
* Command: Shockwave can be used to drag enemies towards you or away from you if you position the ball properly.


Playing Against: Orianna

* Orianna can only affect the area the ball is around. Use this to your advantage.
* Watch out for Orianna's ball returning to her due to leashing. This may cause some unexpected situations.

Pros

Very good zoning
Good early game even without a lot of AP
Can use ball to check bushes
Good Support
Ultimate is good for crowd-control

Cons

Squishie
Targeted in team fights
Can be hard to learn

Orianna is a very unique champion compared to all of the others. She might be considered one of the harder champions to master, but once you do she can be one of the best champions out there. The special thing about her, as you may have guessed, is her ball. Her ball can be used very efficiently for aggression, defense, zoning, and support. In this guide I will be explaining the way I use Orianna and the build I use with her.

As it seems to be custom, here is some proof of my guide's authenticity:
As you can see, in the first game we won so quickly that I never got into the phase of the game where I start playing more of a support role. In the second game, we got further in the match to the point where I was trying to help my team and keep them alive at the same time as dealing damage, hence the 37 assists.

Clockwork Windup- (Passive): Orianna’s autoattacks deal additional magic damage every hit, subsequent attacks on the same target within a few seconds will add more damage per hit. This bonus stacks up to three times.

This is Orianna's Passive move. It is good for hitting a champion to kill them a little bit quicker, but don't expect it to make a very noticeable difference. However if you watch the Orianna Champion Spotlight being hosted by Phreak, at 2:05 you see that Orianna's passive created enough damage output for her auto attack to kill Ashe and achieve first blood right before dying, although it was probably a lucky thing anyway.


Command: Attack- Orianna commands her ball to fly towards target location, dealing damage to targets hit but doing reduced damage for each additional target hit. Her ball remains behind at that location afterwards.

As you can see by the name, this is Orianna's main attack move. It is mainly used to deal damage and for moving the ball in position for your other moves such as Command: Dissonance and Command: Shockwave. You can also use this for zoning purposes and as and alternative to face-checking bushes.


Command: Dissonance- Orianna commands her ball to emit a magnetic pulse, dealing damage to units around it. Afterwards, the ball leaves a field behind for a few seconds that speeds up allies and slows enemies.

When being used offensively you will normally use this ability right after hitting an enemy using Command: Attack. Alternatively you can use this in coordination with Command: Protect on an ally to speed him up and to slow down his chasers.


Command: Protect- (Passive): The allied champion the ball is attached to gains bonus Armor and Magic Resistance.
(Active): Orianna commands her ball to fly to and attach onto an allied champion, dealing damage to enemies it passes through and shielding the allied champion when it arrives.

This is a very good support move for Orianna as well as an offensive move. You can of course use this to shield an ally, but most of Orianna's moves aren't very good unless used in combination with another move. I like to use this on an ally champion and then using Command: Dissonance. This spell combination is also good for team fights, you can use Command: Protect on a melee champion, then use Command: Dissonance to damage everyone in the area.


Command: Shockwave- Orianna commands her ball to emit a shockwave after a short delay, flinging affected enemies in the vicinity into the air a set distance towards, and possibly over, her ball.


Orianna's ultimate move shouldn't be used just to deal extra damage, but it should be used strategically. It is a very good Crowd-Control move and can turn the tide of a team fight. You will usually want to use it when your tank initiates a fight and the other team is partially crowded up. Then you can either use Command: Attack to just send it in to cast Command: Shockwave, or you can use Command: Protect on a tanky melee champion to bring your ball in the middle of it all then you can cast Command: Shockwave. It's all about situation and preference. If you think your tank can survive and doesn't need the shield then by all means send in your ball for some extra damage.

First I like to use Marks of Insight for the extra magic penetration,
Seals of Clarity in order to keep your mana levels high,
Glyphs of Celerity for cooldown reduction,
and lastly Quintessences of Potency for a little extra Ability Power early game.

With Orianna I like to go 9/0/21 putting points in offense to get Archaic Knowledge and then the rest into Utility for the obvious caster masteries. Some people like to put points into Utility Mastery for a longer blue buff, but I find no use with the blue buff when playing as Orianna. With my Seals of Clarity and Tear of the Goddess/ Archangel's Staff there's no need for more mana regeneration. And with my Ionian Boots of Lucidity and Glyphs of Celerity I don't need the cooldown reduction either.

I like to use Flash and Teleport as my summoner spells. I've seen a lot of guides use ghost and flash, but I don't think that ghost is necessary because you can always use your Command: Dissonance to increase your speed while slowing down your enemy's speed. Besides the teleport is very useful for your first trip back to get boots and a Tear of the Goddess. Plus it is always useful to protect any turrets that were being attacked with no one on your team nearby to protect it. (This seems to happen a lot to my team...)

Other spells that could work for Orianna:

Ghost- As I said above, I don't really like ghost because of your speed boost from dissonance it's not completely necessary, but it is all about preference. If everybody played Orianna exactly the same way she wouldn't be a very unique or versatile champion.


Ignite- This spell might work well for some people want to try carry as Orianna, it can effectively finish off an enemy champion before they can run away. I don't normally like to use this for Orianna, but if it works for you then that's great.


Clarity- This spell will be mainly for beginners with Orianna or maybe if you just don't have your Seals of Clarity yet. After you get comfortable with playing Orianna though, I do recommend switching this out for something else as it does become useless late game.


Exhaust- This spell isn't very viable for Orianna. It can help for slowing the enemy down while you chase/run away, but I think that if you know how to play Orianna effectively then you won't need this.


Clairvoyance- This is a very useful skill. It is mostly useful when in a premade with people that you are talking to on Skype or Ventrilo. That way you can plan your movements with your new-found knowledge on your enemy's whereabouts using Clairvoyance. I like to use it to check for ganks, checking in bushes, and checking Golemn or Lizard to see if the enemy jungler is getting a buff so me and my team can mess them up.


Cleanse- This spell might be a good idea when you see that the other team has a lot of crowd control effects, but usually even then I don't really like getting this spell, but again, it is all about preference.


Spells I don't highly recommend using:

Heal- You shouldn't need this to stay alive.
Revive- You shouldn't be dying so much that you'll need this.
Smite- This build isn't for a jungling Orianna.
Fortify- If anyone should get this, leave it for a tank.
Rally- Leave this for someone else if anyone does take it.

First off, I always start off every game with my good old Doran's Ring. This item is always amazing for early game as it gives mana regeneration, ability power, and health. I don't usually buy a second one, but I will if I have to return to the base early and I don't have enough money for anything else. This usually would be the case if I'm not doing so well early game.

If your not busy getting raped early game though here's how your build should look:

On my first return back to the base I usually want to have at least 1,345 gold to buy a pair of boots of speed and a Tear of the Goddess. This will give me more movement speed to dodge skill shots, run, and chase down your prey. And the Tear of the Goddess keeps my mana up. I usually have mana problems early game unless I don't need to harass too much. So this Tear of the Goddess really helps early game.

Next I like to buy my Ionian Boots of Lucidity and a Catalyst the Protector Catalyst Protector. Then I try build towards my Rod of Ages early game to get its stacks as soon as possible. After that I try get my Archangel's Staff. Getting both of these items earlier in the game is a must as it will bring their stats to their full potential fast enough for you to really be able to spam your moves and help your team.

After I get all that I try to get my Zhonya's Hourglass for some survivability and then I buy a Guardian Angel, this item is usually used by tanks, but I like to play early game as more of an offense mage then later game I kinda of transform into a hybrid offense/support.

My last item of the game is a Rabadon's Deathcap, this item gives the most ability power in the game besides a Mejai's with full stacks. You can choose to get a Mejai's early game so you don't have to worry about getting Rabadon's later on. Again, the build is all about situation and preference.

*Update
After reading the suggestions in the comments made by CrusaderMercutio and Jedzc, I did decide to try a few games switching out Zhonya's Hourglass with a Rylai's Crystal Scepter and the Guardian Angel with a Banshee's Veil. I did find Orianna to be more useful with these items as I did not find any situations where I felt I regretted not buying the Zhonya's Hourglass or the Guardian Angel. While I do think my old build is useful, using Rylai's Crystal Scepter and Banshee's Veil gives you better use for your money. I did notice though that getting both a Rylai's and a Rod of Ages might be little bit overkill on the survivability so you can replace the Rylai's if you want with other items such as a Morello's Evil Tome, a Will of the Ancients (although I don't really see the use of spell vamp on Orianna the aura might be nice if you're into that kind of thing), or even a Lich Bane (if you get this be sure that you auto attack while in a fight or else it's a waste of money), it is all about preference.

Also I found that if need be then you can buy Archangel's Staff before Rod of Ages if you feel like you want a little bit more AP earlier on.

Here are some optional items that you may consider:

: These are always good for a caster as it will give you some extra Magic Penetration if you don't care much about you Ability's Cooldowns.


: This is a good item as it will increase both your health and ability power while also adding some slow to your abilities. This could be a viable substitution if you want some more survivability or need help catching up to or running away from your enemy. Either way the slow will help.


: This item is a good choice if you are facing a team that is stacking Magic Resistance. I wouldn't recommend getting this item if they don't have a lot of Magic Resistance, you would be better of buying another item.


: This item can also be a viable replacement if you don't feel like going the extra mile for a Guardian Angel and need more Magic Resistance instead.


Philosopher's Stone : This could be a good replacement for early game. I wouldn't recommend building into this if you are planning to buy a Doran's Ring in the beginning. If you want this item you should incorporate your beginning items with the items needed to create this quickly.

Early game I like to max out my Command: Attack and Command: Dissonance for some good harassment early game.

Orianna's ball is very good for offense, defense, harassment, and zoning:

Her ball can be used to attack multiple enemies at once, but it is most effective when used on a target champion without it passing through other enemies first.

Her ball can be used for defense by using Command: Protect on yourself or on a target ally to give them a shield and some extra Armor and Magic Resistance. Her Command: Dissonance can also be used to "protect" by slowing down enemies or speeding up allies, or sometimes even both.

Orianna can harass very effectively using her ball and using Command: Attack. Just leaving it out near the enemy champions will scare them which also provides a good zoning bonus as well. What I love about her ball is that you can use it to check bushes for enemies. This is very useful at destroying your enemy's zoning plan and creating your own zone of defense.