Before I start telling you about my Orianna build, let me first tell you about myself. My summoner name is House Paint on the NA server. I am bronze 1, partially because of the fact that I never play ranked, and partially because unfortunately, I don't always get the best of teams. This does NOT mean that I am bad (mind you I don't claim to be good). This is my first guide, and it's for a build that isn't meta, but works very well in the current meta.

Now, with that said, lets move on.

This build is entirely about DPS, and having the ability to cut through tanks, especially in the late game. Now I know you are thinking "Why not play an ADC or Cassiopeia or a champ that is meant to do DPS?".

Well the problem with ADC's, is anybody other than other ADC's will end up with between 100-250 Armor. You can build Armor penetration, but beefy armor scaling tanks (Taric and Rammus) will still laugh at any adc's damage. The advantage to having an AP champ doing nearly as much damage, is that the enemy team can't just stack armor and health and force your AP to blow all of their spells and then have to wait on cooldowns. They Need to build some MR, increasing the damage dealt to them by your ADC.

"Okay, but that still leaves Cassiopeia and the like." Yes, they do still exist, but the advantages to Orianna over these AP champs bound to spells are:
1. Not relying on mana for damage- You won't get caught without mana and be absolutely helpless.
2. The Orianna ultimate- One of the best AOE CC ultimates in the game is on your team.
3. Farming- goodbye are the days of missing CS, because you obliterate all minions and jungle creeps in your path just with your basic attacks.
4. Magic Resist- By having two viable items that reduce Enemies Magic resist that both grant magic resist, instead of just one, magic resist and busty AP champs won't stop you. You will stop them.

Now, the reasons that you might be hesitant to use this build. (I cri ;~;)
1. She is a mana *****- 'Nuff said.
2. Minimal sustain in teamfights- Unlike most mages, who would mash their keys like a madman and then run to the backline, you are doing sustained damage, you aren't leaving that fight until you have to, or the enemies die. Champions that have spellvamp, lifesteal, or are just in general tanky enough to take a lot of damage will survive much better than Oriana, who will die very fast if she hard focused.
3. Lack of burst - Unlike a normal Orianna build, you can't do buttloads of damage to all enemies that are unlucky enough to get caught in your ult. You do have a lot of AP, but not nearly enough to instantly pop carries with the damage from your Q>R>W>E>Q combo. You have to basic attack them.

Runes, as you saw above I only have 1 rune page, and that isn't it. My MR/AP/Armor rune page is plenty good enough for every champion I play (adcs included), so I'm no rune expert honestly.

In terms of items what you are going to need is on hit AP items, mana (they should make a mana hog Ori skin, my god.) and attack speed.

Lich bane - This item will give you LOADS of damage after every spell you use, and with the low cd on Orianna's q, this is a very good item with this build.

Nashor's tooth - granting AP and attack speed this is already a really nice item, the juicy Ap scaling basic attack passive only makes it better.

Wit's End - this item gives you magic resist, magic resist STEAL, and quite a bit of attack speed. It also gives you a little bit more AP damage on your basic attacks.

Seraph's Embrace - Mana and AP. Plus AP scaling from your mana... and a shield. Oh, and you kinda need it as Ori. just saying.

Abyssal Scepter - As well as giving AP and MR, it's Magic resist reducing passive is big enough for Ori's basic attack range. YAY.

Void Staff - Just to make sure that those MR stacking Galios cry at night.

(more items to be added with updates)

Like most other champions, you want to level up R as soon as you can. This build is all about DPS, so maxing Q first is ideal. I have always maxed W second for more damage, but maxing e second instead could also work well (I'll try that in my next game as Ori).

Jungling with this Ori build is actually pretty decent. Just replace the wits end with purple smite and a devourer. You'll end up doing a little bit more damage from stacking later on. You should be able to go Gromp> blue> wolves> red> krugs just fine as long as you smite red. That will give you enough gold to get your pusple smite and some other stuff. When jungling, you want to take Q->E->Q->W->Q, after that leveling abilities goes back to normal. You won't take too much damage from camps, and with purple smite, you should be able to sustain your mana well enough to farm the jungle just fine once you have a few tear stacks, even without blue, although blue is highly recommended.

Ganking can go anywhere form horribad to amazing to just funny. By being squishy, ganking a prepared laner can end up with a dead robogirl (cri ;~;). When ganking with Ori, you can get creative with things, whether that means flash ulting the enemy support and adc for a double kill, or leashing the ball to your ally and having them jump on the enemy for you to cc, or ganking like a normal human (robot?) being and walking into lane and slapping people around with a ball. Just make sure your laner knows that you are ganking, otherwise nothing will get done.

Orianna is a very strong champion even with a normal build, it is my personal opinion that this build is even stronger, as if makes her not only force the enemy team to behave different, but also gives you a much higher damage output in general by abusing her passive. If you have any thoughts, questions, tips, death notes, snacks or anything else, feel free to comment, as I'll be updating this at some point later once I've played a few more games and tried some other stuff. I hope at some point you can try what I put in this guide (can you even call it that?), or at least found it interesting.

Thanks for your time!