Not Updated For Current Season
The masteries shown here are not yet updated for the current season, the guide author needs to set up the new masteries. As such, they will be different than the masteries you see in-game.
First of all,sorry for my english xD.
Orianna is a very versatile champion, she can play as ap or support but she is quite difficult to use, even so, is very fun to use ^^
The skill sequence is: Q+W to damage the enemy, when they are damaged use Q+W+R you can also use E on an ally and use your ultimate from him.
Orianna needs runes of magic regeneration, but its not really necessary on midgame-lategame, so you can chage it and take ap runes.
the quintessences of movement speed are also a good option if you have enought ap.
Pros / Cons
lot of versatility
very fun to use
great damage and support
lot of range
waste lot of mana
difficult to use