Alright, so i decided to make a guide for Orianna because i see alot of players trying her out and not really highlighting her strengths to truely let her shine, so here goes: (this is my first guide, so any advice would be appreciated)

i go with magic pen marks, mana per 5 per level seals, and ap glyphs/quints.
the reason for this being that while i know flat mana per 5 seals would make her early game easier mana-wise, you really SHOULD NOT be running into mana problems early game if you are using her skills properly (more on that later) while late game the 'regen' from catalyst/RoA tapers off and then goes away all together, so this extra mana/5 boost i find to be really useful.
i really prefer to get my cdr outside of runes, and i find that the boost to early game ap is incredibly helpful in establishing yourself as the dominant factor in your lane, and often getting first blood - as such i go for the ap seals, as well as quints (yes i know magic pen quints would be much better end-game, but in my opinion it is more important to give yourself the greater advantage early-game as orianna, and then focus mainly on support as opposed to damage end game)

masteries are pretty straightforward for a caster, and if you have certain playstyle preferences by all means go for it, but i really reccamend this set-up as it will allow you to give a solid boost to cdr, max nuetral buff durations (blue is great for orianna, and fairly easy to grab solo) and get the most out of your summoner spells, which is a huge plus in my book.

i go for flash and ignite on ori.
flash is just huge - escape, chase, buy time, save a friend... its all purpose, and ive never once regretted picking it on orianna, a must have.

as for ignite, i know quite a few people will argue that its only good for finishing off runners, and that you shouldn't have people getting away with your 'w' spell, but i find this to be fairly inaccurate. the fact is that ignite will help you do that extra bit of damage to snag first blood, it will help you kill those pesky champs with low hp that don't need movespeed to get away (kass/ez/etc types). it will get a kill you wouldn't normally have gotten against teams with healers, or drainy types like swain, and lets you put the fear of god into tryn.

if you have an aversion to ignite though, teleport is a viable option to maintain lane dominance, or if you really wanna focus on the support side of your role with your summoner spells, exhaust is also viable - use it to secure a kill for a lanemate when your w is down, save an ally from a gank, etc.

again though, i really recommend ignite, in my opinion it just really helps to fill in some of the gaps between her skills.

Passive - Clockwork Windup: this boosts your auto-attack damage based on your ap, and how many times you have already hit them with an auto-attack. a welcome bonus, this helps orianna do decent damage between attacks. it is not however, something to focus on; do NOT build attack speed items, its just a waste.
Command: Attack - This is Orianna's bread and butter; and it has two key uses. First of all, attack will send the ball to target location, where it will stay until you pick it up, send it to attack somewhere else, or protect.
ALWAYS BE AWARE OF YOUR BALL'S LOCATION.
i really cannot stress this enough, as it is the most important part to playing orianna. know where your ball is at all times, know how long it will take to travel from where it is now to where u want it to attack next, and know whether or not you will be able to send it somewhere new if you suddenly need to. - This mostly pertains to how you use attack and guard together. basicly, in order to do well as orianna you want to always be able to move your ball from where it is now if you need to even a second later - you're doing no one any good if your ball is guarding ashe way off in the back and your command: attack is down; you are also no longer doing any one any good if your ball is ontop of the corpse of an enemy ashe way in back, and your attack and guard are down.
early game, you want to use your command: attack to harass as often as possible. also keep in mind that it is great for killing minions. This means that if you dont want to push, you have to be very careful to not send ur ball through a wave to harass, or you will quickly find yourself with a fully pushed lane, exposed to ganks when thats not what you wanted.
basicly, there are two main 'attack routes' for your ball. the first is to keep it BEHIND the enemy ranged creeps, so that you can sweep it from side to side to hit enemy champions as they run forward to last hit, but you wont hit the creeps themselves and push.
the other is to place the ball right next to the ranged creeps, sweeping the ball through them to harass champions. this method will do less damage to the enemy, and push the lane, so use it only if you are setting up for a kill, or you are confident that you can keep your enemy zoned even with a tower there.
Command: Dissonance - this is an incredibly important spell; powerfull, versatile; expensive. To be perfectly honest, you can tell the difference between a good orianna and a novice one simply from watching how they use this spell alone. when activated, it does damage in an area around the balls current location, and places a 'speed zone thingie' there. allys walking in get sped up, enemies get slowed down.
Effectively, this makes gives a single spell 3 key uses. first off, it does some pretty good damage, particularly when linked properly to your attack command and your ult.
far more important, however, is the speed boost. use it after an attack to slow your enemy and close the gap to finish them off, use it when the ball is on you to get away from even the most deadly ganks. (flash first if things are really hairy) or send your ball to guard a friend and then speed boost them so they can escape - also if running away with a friend, make sure whoever is infront is the one you guard/speed boost, so that you both run through it.
for all it's uses tho, dissonence is pretty darn expensive. DO NOT SPAM IT!!!!
thats right, dont spam your highest damage ability... i know it sounds crazy, but you wanna SAVE dissonence. poke at the enemy with attack until they are scared to go near any minons and are pulling their own hair out, but do not use dissonence unless:
1. you are going for a kill (and i dont mean you think you will kill them after 2 more rounds of pokes, i mean right that second)
2. you are saving your own life/someone else's
3. its mid-late game, you dont have champions near you, and you are trying to quickly wipe a minon wave.
the reason for this is simple; missing with an attack/dissoence means 4 secconds of open season for your enemy, which is bad enough, but spamming it also means being very oom, having your lane constantly pushed even when you dont want it to be, being without an escape when you need it, and giving your enemy plenty of notice as far as when they need to back; spam poke with attack, and save dissonence for that special occasion when someone gets to die ;) (or you dont want someone on your own team to) this lets you hold you're lane for as long as you want to.
Command: Protect - a very solid support skill, as well as lending you additional ball control. This ability sends your ball to your friendly target, shielding them on arrival and then giving them increased mr/ar while it stays on them. the ball will move with them too, so you can use this to make sure your ball is in place for ult and dissonence by throwing it on your team's innitiator, while also giving them a surviability boost.
guard also deals damage equal to half of its shielding value to anything it hits along the way that isnt friendly, so linking attack and guard can help you cheaply clear whole creep waves - throwing guard on the singed infront of your running enemies will both damage them, and position the ball nicely for a slow with dissonence, etc.
Command: Shockwave - Probably my favorite ult ever. its not a game changer like some, but once you have an handle on how to use it, the possibilities are endless. just remember that the distance it pulls enemies is always the same, and it allways pulls them towards the ball. this means that if the ball is directly infront of them, they will launch over it. if the ball is directly behind them, they will launch behind it. if there are three enemies spread out in different directions, but all along the outtermost range of a well-thrown dissonence, they will all land ontop of the ball and eachother. it takes some time to learn, but with practice you will know exactly where that pesky enemy will go, and exactly where to position the ball for an ult to throw them where you want them. once you get it down, use it to:
throw enemies into your turret
peel enemies off your friends, allowing for an escape
pull enemies towards your friends, so they cant get away
throw enemies over your shoulder as u run through them to get away (ult + w after the throw)
throw enemies infront of you as you juke sideways into bushes (again, use w too)
stack enemies up for your w to do solid damage, and set your allies up for their aoe abilities (orianna and a friendly kat make for great friends)
disrupt enemy channels - from malz ults to ap yi heals; stop them from doing whatever they are doing so you can bring the pain

just remember, your ult does have a delay, do not use it if the enemy is going to be able to run out of its range before it goes off, and make sure your team doesnt depend on you soley for disrupting things like kat ult, as between travel time for your ball to reach her, and delay time on the ult itself, your team will have already taken alot of damage: you should still be disrupting what you can, but make sure your team know whats up.



now, for important combos:
+: this is your slow + high dmg combo, use it when you are going for the kill. remember that you want to throw the ball THROUGH the enemy to a reasonable distance infront of them, hopefully making it so that while your 'w' is still doing damage, they also have to run through half of the slow zone or more before they are free.
++: the best way to sew some serious confusion while doing major damage and slowing a group of enemies in a team fight. just make sure that you know where your ball is going, if it is directly ontop of your intended targets, dissonance FIRST, as ult might very well throw them out of range, then when they start running to get out of your slow zone, use your ult to finish the dmg combo, disrupt, and throw them right back into the center.
if your enemies are more spread out though, use your ult after your attack, to pull them all directly ontop of the ball, then dissonance.
+: this is your utility combo, use it on yourself to get away, use it on your friends to save them.

there are 10 or so more that i could go over, but in all reality once you get the ones above down, the rest are just natural evolutions of the bigger ones for more specific situations - you will figure them out naturally on your own as you learn the champion.

alright, so a brief explanation of my build is the following: i start with ring - it really does have everything orianna needs early game, extra hp to help manage the squishiness, enough mana regen to let you spam attack fairly liberally even at level one, and some ap to help you put the fear into them. next back get your boots as a minimum. if your doing well, pick up one half of your catalyst, and an hp pot or two just to make sure you can stay in your lane until you can finish your catalyst. from there finish into rod of ages. this is important for orianna because it not only provides some great regen early-mid game, but it also helps give you some much needed hp.
after your rod, upgrade your boots to lucidity, and from there build yourself a fiendish codex. after this point its more situational - if you are doing well, your mana regen is fine and you are hitting your targets hard enough that a q+w combo is hitting for 40% hp or more on their teams non-tanks, build your codex into morello's so that you can keep spamming as often as possible. if you need more damage, build your deathcap after codex. whichever you choose, make sure to build the other one after that.
once you have your morellos and deathcap, the rest is really up to you.

if you are doing well with kiting the enemy and largely staying out of harms way, grab a lichbane to really boost your dps.
if they are building tanky, and you need some mr, go void staff or abyssal scepter, depending on how tanky they are building and how much magic damage they have going on.
and if you have some carries that are giving you a hard time, build zhonyas for bursters, or GA for the more sustained ashe/yi/tryn types.

if somehow you have built 5 items and the game is still going, revisit the list above ;)

so.... thats my orianna guide. again it is my first guide, and any tips on the build, or stylistic advice on the guide itself would be greatly appreciated. please tell me what you think!