Level 6 Orianna with 35k points, she's great mid lane, her problem is dealing with ganks since she doesn't have reliable cc (stuns roots snares) without her ult but you can't rely on your ult everytime you get ganked, most mages do which makes Orianna weird
She has complex skill shots but can zone and harass very well if played right, last hitting minions is good because of her passive. She was super strong around 6.18 but now there are so many "op" mid laners that she struggles against, if she gets out ranged she gets punished pretty bad, but she can fare well in many matchups
i recommend taking her mid since bot lane has been the most unbalanced for a while now, especially with the buff to lethality, and mage supports are good but she works much better mid. If you get fed with Orianna she does massive damage, overall, she's a fun champion that is rewarding once you learn her but she's not a champ you can always play because some matchups are just way too difficult to come out victorious
As for her playstyle, try not to use your spells too often, save it for when you can land your QW and land an auto to proc thunderlords and zone them away from minions. You should focus on farming and go for the QW auto poke whenever they're out of position, if you think they're low enough and you have your spells, go for it, your ult can pull them back and stun them just long enough for you to land everything, if you have your jungler, it's almost a guaranteed kill. Don't forget you can shield you allies or yourself with your E which can save you from poke or the last ticks of ignite, or just to not take so much damage from a turret shot. In lane you wanna max Q, then W, and E last, upgrade R whenever you can of course, as with most ultimates
Some cool tricks with Orianna would be learning to use her utility to her advantage, her W makes a small area which slows her enemies and speeds up you and you allies, if you have your ball on you, use this to run away faster from a gank, pared with
, you should escape a gank easily. If you get caught however, her ult is super neat, always remember that it can pull people towards it, meaning that if you're gonna die and Lee Sin is on top of you, you can place the ball behind him with Q and quickly R to pull him away from you giving you time to run, a prime example of using your ult for escaping would be this clip of Faker using his ult to pull Jayce away from him, and shielding himself afterwards which allows him to survive the gank, here's the clip :
https://youtu.be/MpT3BX4rlkc
TL:DR always remember, you have a shield on E, slow/speed up on W, and a pull away on your R, QW auto for thunderlords to win trades, and max in RQWE order, I like to take Flash and Ghost because Ghost is very good for getting out of ganks but Cleanse is always an option if you're against someone like Veigar who you don't wanna get stunned by or else you'll die, best of luck to you on the rift !