Gives you a nice amount of MPen right from the start. Extremely useful Earlygame, but falls off a bit lateron. Due to the fact, that Runes are most helpful in the beginning and we build some more MPen later, this is no big Problem.

In the current Meta you will most likely face another Caster in Mid, which makes Magic Resist the first choice in Glyphs. Also very important, because Banshee's Veil is going to be our only Item, which provides MRes.

greater seal of replenishment
These Seals grant a decent amount of Mana Regeneration, which will be a big issue in the first seven or eight minutes. The Summoners, who prefer to start with Meki Pendant, can replace these by Life/Level or Armor Seals, but because we start with Boots and will have Blue from the seven Minute mark we don't really need the additional ManaReg.

My Summonerspells in nealry 95% of my Oriannagames are


+


Flash is and overall useful Spell, you will find yourself using it to close the gap to an enemy, hop over walls, get away from ganks, etc. Even after the nerf the best Summoner Spell in my Opinion.
Ignite is also a nice spell, dealing true damage(!) to your enemies. One of the safest ways to finish of a running low-health-enemy, because there are not many ways to survive it (in Top- and Mid-Lane there won't be many ways to heal and Cleanse is rarely seen).




Teleport is the only alternative I see for Orianna, and this only in the case that you have to go Top. With her Command: Dissonance she can change lanes quickly enough for a gank and doesn't need to teleport in. Command: Dissonance is also the reason, why Ghost is not that helpful on Orianna, it just works as a built-in Ghost.


All the other Summoner Spells are either useless on an AP-Caster or just fall off the longer the Game goes ( Clarity).

Starting Items

Your normal choice should look like this: It helps you do dodge any kind of skillshots, you have a nice amout of survivability and in combination with Command: Dissonance you should be fast enough to run away from ganks safely.


Doran's Ring is an alternative start and does a great job on any Caster. Nevertheless I feel much better having boots right from the start, because the mobility just is way more important for my playstyle with juking forward, backing off immediately etc. Doran's Ring is my number 1 choice if I have to go back without having the money for Catalyst the Protector

sight ward
A very unconventional start and only recommended if you don't expect to take much damage. Viable against matchups like Vladimir Mid and a strong Jungler with early Ganks like Lee Sin. In this case it's important to level up your Command: Protect to outsustain the harrass. Go back at about 600-700 Health and get a chunk of Health Potions and maybe a Sapphire Crystal.

Core

catalyst the protector->->->
Your main objective is to get catalyst the protector as fast as possible, because it gives you a decent amount of health and Mana. The Regeneration at Level-Up will let you stay in Lane as long as you want without having the necessarity to go home. Strictly run to build it in a Rod of Ages out of it to benefit from the increasing stats as soon as possible.


After finishing the Rod of Ages you want to grab Ionian Boots of Lucidity as your Level 2 Boots.

Why Ionian Boots of Lucidity over Sorcerer's Shoes?
Orianna is one of the most CDR-dependent CHampions in the game, beause she needs to keep her ball moving constantly. 15%CDR will greatly increase the amount of skills you can use per minute and therefore increase your damageoutput.
Sorcerer's Shoes bring 20 flat Magic penetration with them, which would bring the enemies MRes to 0 in combination with your Runes and Masteries. But the longer the Game goes, the more these shoes will fall off, reduced cooldowns are good at any stage of the game. For MPen we are building Void Staff later.

Mid-/Lategame-Items

The Infinity Edge for casters, pretty self-explaining, I have rarely seen any caster without Rabadons.


After Rabadon's we want to build up some defense to survive the Teamfights which should start right now. Banshee's Veil is maybe the most popular Magic Resistance Item alongside with Force of Nature. The Spellshield can save you from these dangerous Dark Bindings or Rocket Grabs and make it very difficult for the enemies to initiate on you. On top of that it also gives some more Health and Mana, which synergizes well with Rod of Ages, which should be fully stacked now.


A wild LeBlanc appears and your abilities are on CD? No problem, we just use this awesome active and noone can touch us for the next two seconds. Zhonya's Hourglass is one of the best items which exist for Casters. 100AP, 50 armor and the buttsaving stasis are insane for the price you have to pay for it. Although it gives great offensive Power I mainly see it as an defensive Item. The armor is becoming necessary now, the Carrys have Phantom Dancer and Infinity Edge and without any armor you just die after casting a single spellcombo. With this Item you just turn golden and let our team take the carry down while he wonders what happened.


If the game went so far even the biggest ****** has built some magic resistance to couter the metal lady. U mad bro? We just build a Void Staff and just kill them like before. Connected with your masteries your have 50% Magic Penetration now, not to forget the MPen you get with your Runes. The 70 AP (91 with Rabadon's Deathcap) are another boost to your damage output.

Why don't you take...?

Lich Bane can really be an awesome item on Champs like Twisted Fate or Cassiopeia, on any casters who can constantly throw one spell after another, so that the Passive can proc as often as possible. As Orianna you will normally throw your Combo without autoattacking between, because the enemy will just walk out of the balls range while you try to get your basic attack off. I see Lich Bane much stronger on other casters than on Orianna


WotA is one of the most cost-efficient items for casters and it can really work nice on Orianna with all her AoE-Abilities. My Problem with that combination is, that due to your shield your life will never go down enough that is was worth buying a Will of the Ancients


Morello's Evil Tome connects a decent amount of AP, Manareg and 20%CDR for a very low price. Looks like the perfect Item for Orianna. But let's face the facts: As Orianna you always want to have Bluebuff. Always! From the second Blue you are going to take every Blue you can take. And alongside with the improoved ManaReg it also gives 20%CDR. These 20% plus the 15% from Ionian Boots of Lucidity give you already 35%, which is just 5% under the Cap (finally found a setup where the 5% of Randuin's Omen would fit :D). So the CDR, the main reason why to buy Morello's Evil Tome would be completely wasted. Additionally you had to sacrifice one of Banshee's Veil, Zhonya's Hourglass or Void Staff which are all essential for the build. For me, Morello's is an Item that you get when you go double AP, the one, who is less blue-dependent can grab Morello's and is fine. We take blue so we don't take Morello's Evil Tome.


Great Item on the majority of Casters. Gives a huge Healthboost, great AP and that cool passive that slows everything you hit. Orianna already has a strong slow, so she really doesn't need 15% extra slow, you wouldn't even recognize it.


Nashor's Tooth is the best CDR-Item in game. But same as Morello's Evil Tome we don't need more CDR. The AP would be nice but Attackspeed? Again, when you start to go into the fight for autoattacks then you are doing something wrong. Although we have built some survivability we won't survive 5 Seconds when in close combat.


Abyssal Mask is a very viable alternative to Banshee's Veil in my opinion, but I would just recommend it, when it is really going well. Remember that you give away your spellshield and some nice Health and Mana, but therefore you get another AP and and an Aura, which reduces the MRes of nearby enemies by 20. Can be compared to advanced Magic Penetration which is useful for all your Allies.