This is my guide on how to play Ahri. I seem to do fantastic with her with this build and playstyle and am sharing it with all of you. Here we go

Magic Pen Reds - Every caster should have them

Armor Per Level Yellows - I like these because armor is one thing Ahri lacks. And there is nothing really good with armor to build on her. Sure you could build a Zhonya's Hourglass on her, but I preferably don't like that item on her. There is really not a time in which you need to use the active on that item. A little armor early helps sustain you through the jungle ganks also.

Ability Power Blues - A lil early AP never hurt anyone

Movement Speed Quints - Ahri is slow. Yes she has high escape and chase, but this is only when her flash and ult are up. You often find yourself wishing you had more speed when you play her and these give you just that.

9-0-21 gives you enough damage without getting greedy, but also enough lane mana sustain to get you through your laning phase.

Many of you might not like my build because i max Fox Fire first. This is ok. You will be missing out. Fox Fire is your main source of damage on Ahri. Not only this, but it is also GUARANTEED to fire upon champions as long as you are in range of them. It is not a skill shot like your other spells. Try putting 3 points in it before you get your ult and have all 3 Fox Fires hit an enemy champion. Melts their HP. With a relatively low mana cost and short cooldown it is definitely the spell i would max first. Some of you might ask why i put a point in charm at level 2. Well this is a good survival spell early game. I usually dont go for the mid gank until im level 6. I concentrate on farming and ignoring the enemy harass. Charm is an EXCELLENT tool to use when the enemy jungler comes out to gank you. Just land your charm and fall back. Gank avoided. Trust me, You'll be surprised at how safe you feel just having your charm spell up while laning. The other skills are pretty self explanatory if you've ever played Ahri before.

Many of you might question my item build as well. But this build is definately going to give you the most sustain, most surviveablility and most burst damage that you can get having all three. Every Ahri should work toward a Hextech Revolver first. It is amazing how long you can stay in lane with the spell vamp it gives. Ask your jungler for blue buff and you can spam/heal all your abilities like crazy. After i get my lane sustain, I like to get my gank sustain. Building a catalyst gives you the mana/health you need to survive a burst attack or jungle gank. Build this into your Rod of Ages after to start stacking that AP and HP. After your ROA i like to build a WIll of Ancients. More AP/More Spell Vamp ftw. Not to mention It gives off the Aura to help out your teammates. This will be just about the time laning phase is over and your teammates can use the aura. Convince one of your AP teammates to also build a WoA and stick close together. Yes they do stack. Can you say 51% Spell Vamp. And when your passive procs 75% Spell Vamp. Uh, Yes plz. I like to get Ionian Boots of Lucidity after my Will. Is it too late to be getting Level 2 boots? I don't believe so. Maybe it will work for you guys to get them before your Rod or before your Will. Whatever works for you. Why boots of lucidity? Its like having a constant blue buff on you. Cooldown Reduction rapes on Ahri. Couple this WITH a blue buff and your just about at max CDR. End game i will trade these for Sorc Shoes becouse i will already have enough CDR. Rabadons is next for the massive AP boost. After you get this you become extremely OP. Especially if you are fed and above everyone else in CS and Levels. Now after Rabadon's is when your build is going to change. It has all been your core build til now. Here is my suggestions based on enemy team comp, etc.

Heavy AD team. Frozen Heart, Rylais Crystal Scepter.
-Frozen Heart gives you mana, CDR, a tonnn of armor, and that amazing aura that reduces the attack speed of your enemies. So much better than a Zhonyas hourglass in my opinion.
-Rylais- Gives you health and AP. But your really using it to kite your enemy melee carries. End game you should be at 40% max CDR, and are able to spam your abilities quite well. They shouldn't be able to touch you. And if they do, slow them and heal up with that spell vamp.

Heavy AP team. Abyssal Scepter, Morello's Evil Tome
-Abyssal- Magic Resist, AP, and Pretty much Magic Pen. Great Item for heavy AP
-Morello's Evil Tome- That ever important CDR, and more AP

Heavy HP team (lot of tanks or tanky characters). Void Staff, Deathfire Grasp
-Void Staff- AP and magic Pen, self explanatory
-Deathfire Grasp- CDR, AP, and that tank shredding active.

Pretty Balanced team. This is a toughy, i usually see who is fed on their team the most or doing the most damage to me and build around them.

Flash/Ignite - Flash is to save your *** or land the kill when your ult is down or before you have your ult. Ignite is to finish them off or to cast on that heavy regen character like mundo or the person building alot of spell vamp or life steal.

That's pretty much my build. Have alot of ranked slaughters with her and absolutely love this new Champion they came out with. She is definitely my new main. Would love to hear some constructive criticism, compliments, concerns, etc. Thanks guys!