Orianna
Like Clockwork
Lane harassment and consistent damage output.
Sorcery
Empowered abilities and resource manipulation
Summon AeryYour attacks and abilities send Aery to a target, damaging enemies or shielding allies.
Manaflow BandHitting an enemy champion with an ability permanently increases your maximum mana by 25, up to 250 mana.
After reaching 250 bonus mana, restore 1% of your missing mana every 5 seconds.
TranscendenceGain bonuses upon reaching the following levels:
Level 5: +5Ability Haste
Level 8: +5Ability Haste
Level 11: On Champion takedown, reduce the remaining cooldown of basic abilities by 20%.
ScorchYour first damaging ability hit every 10s burns champions.
Inspiration
Creative tools and rule bending
Triple TonicUpon reaching level 3, gain an Elixir of Avarice.
Upon reaching level 6, gain an Elixir of Force.
Upon reaching level 9, gain an Elixir of Skill.
Cosmic Insight+
18 Summoner Spell Haste
+10 Item Haste
Adaptive Force
+9
Adaptive Force Adaptive Force
+9
Adaptive Force 
Health Scaling
+10-180 Health (based on level)
Why Summon Aery
Aery is an incredibly reliable source of damage in the early to mid game. It's also very strong in scrappy fights thanks to the bonus shielding on your [E].
Why Manaflow Band
Spamming abilities for lane pressure is Ori's forte and Manaflow Band enables her to do so very regularly.
Why Transcendence
Stacking CDR on Orianna is a priority and in doing so you gain significantly more damage.
Why Scorch
The safe harassment range on your **[Q]** makes for an easy proc on Scorch for lane pressure damage.
WhyTriple Tonic
Zhonya's is a strong item on Orianna in many situations and Perfect Timing helps you hit that power spike even sooner.
WhyCosmic Insight
Cosmic Insight synergies very well with both Transcendence for CDR and Perfect Timing for a lower Zhonya's cooldown.