Hi im a good eloed player who is on his way too diamond. I am going full ham on getting there. I play Ahri, jayce and vayne in my ranked game, taking top- and midlane or if i get the chance the vayne of true damage botlane.

Im gonna tell you about my setup for midlane Ahri - The assassin of temptations.

For runes you will be going Ap together with magic res. for the early lvls.
You have taken some late game armor per. lvl seals and exp quints.
This will hellp you reach lvl 6 before your opponent

Setup is pretty basic.

Item are just everyhting that builds of the naughty item "needlessly large rod" ;)
It's just not the item name that makes you build her with it, but rather that i think riot named this item for her.

Cause you know.... riot pls nerf.

For the setup on skills you go for maxing Q for the high damage output and secondly your charm to lock down enemies longer and help out with ganks by making them not able to retreat to tower.

For summoner spells take flash and ignite or teleport and ignite.

Your gonna take flash for extra positioning in lane, but you don't need it since you have three dashes on your ult, but i like the idea of having four.

Taking teleport instead of flash provides extreme ganking power and utility around the map.

Taking ignite gives you bonus damage in a fight and the power to shut down heals from your opponents.

To summarise what we have been through so far, we have a lot of offensive on ahri and a good set of utility and CC to go with her damage.

In ranked play you would be cs'ing until lvl 6 where you then can go for some serious plays.
You will use the lane pressure you can generate thoughout the game.

And in fights stay in the back charming all that go for your adc. And when they are weak and low on health you will rush in with ult to take down the last ones.

pros:

High mobility
Strong mid- to late game
Heavy CC
True damage
Non Squishy
Ranged

cons:

Weak early game
Easy shut downed if CC'ed
Hard to perfect
Hard to get back into game

Not really anything you need but taking wraiths if your lane is pushing and enemy is at their tower defending can be a good thing.

And the Q will kill the smaller minions early game and W will finish the bigger one of.

Taking blue buff is a must for Ahri, if your jungler is nice try to ask him for the first blue buff.

Teamwork is hard on Ahri because she is a solo champ. Only thing you can help with is landing charms and taking down your opponent.
You don't have any spells that buff freinds so your gonna be the leader in fights and see the chances for kills.

Super awesome tricks!

If your fed and rushing into two enemies charm the one that has CC so you can kill the other without interrupsions.

Using charm on enemies will slow them if your running from them, you they will not lose track of you but they will get slowed and fall behind.

Using flash before popping ult when engaging will let you hit ult and gain that extra damage.

Your ult can jump walls and you can often pull a lot of tricks with it.
You can jump over and if they flash after you, you just ult back again.

Your only real farming ability is Q and when you get your AP you can one-shot minions. Making it easier to get even more AP.
And keep farming until you hit 6 or 8 and then go in for plays rather than minions. But keep up the CS, you will always be needing gold because Ahri's rods are expensive ;P

So i hope you find this usefull in many ways, helping you climb ranks or just making better plays with Ahri.

I am also making plays with this and hoping for you to do the same.

Anyways good luck and high five in your future Ahri games.