Hi!
I've been playing LoL for about a year now and I like to play mid.
So, here is my guide on Ahri^^

21/9/0 is the best way to get Ahri some extra stats.I dont really build into much ad cause it wont really help the only ad you should use are Fury, Butcher, and Feast.In def you just get sustain so your not quit so squishy.

(Passive) Essence Theft

In lane when it is ready try to use it with Orb of Deception on all minions and champ for full heal.
If you run by a camp just use this passive with Orb of Deception into camp for heal or for a couple more stacks
If you are solo against champ it is better to use Fox-fire because each flame counts as a spell giving you more heal
Use this with Charm the least you can because it does not give mich heal

(Q) Orb of Deception

In lane use this to poke and harras your enemy real bad and get massive heal with passive
In Team fight try to use it in a Combo with Charm and Fox-fire

(W) Fox-fire

This ability is best used in combination with Charm and Orb of Deception
It can also be great with passive when soloing enemy champ
Or to do good damage to push away enemy during gank

(E) Charm

In lane use this to pick the enemy in combination with the rest of the kit
This ability is also the trigger for most of your combos
In team fight use this ability to pull an enemy out and combo them for lots of damage

(R) Spirit Rush

In lane use this to anitiate and aim a Charm for combo
In team fight use this ability to chase down fleaing enemys and to get out of fight
This ability is also good to prevent death by rushing over walls
It is also a great juke tool

So, thanks for reading my first Mobafire guide,I know its a little short but I hope it helps
And lots of fun playing Ahri!!!