Hey everyone.
My name is Asio, I play on EUW, and welcome to my Ahri guide.
Ahri has been my favorite champion for a while now and i felt like making a guide, so here we are.
This guide is for both new players and experts.
Have fun reading it and I hope it will be useful to you.
Now "Let's have some real fun."

Pros

- Ult is useful for escaping and chasing
- Not squishy with this build
- Strong nuker
- Good farm with Q
- High sustain (Spell vamp)
- Charm and Rylai's will give her some CC.

Cons

- Item dependent
- Can't carry against fed enemies
- Needs a good early game to shine in mid-late game
- Vulnerable to CC

Essence Theft (Passive)
Ahri gains a charge of Essence Theft whenever one of her spells hits an enemy. This caps at 3 charges per spell cast. Upon reaching 9 charges, Ahri's next spell will have 35% bonus spell vamp.

This passive can save your life in the laning phase.
It can hold you in the lane for a very long time. Combine it with your Q on an incoming minion wave for full potential.

Orb of Deception
Ahri sends out an orb in a line in front of her and then pulls it back, dealing magic damage on the way out and true damage on the way back.

Very good attack because of it's true damage, and has a good range.
The enemy will be scared of you if you manage to hit them with this.

Fox-Fire
Ahri releases three fox-fires to surround her for up to 5 seconds. After a short delay after cast, they will target nearby enemies, prioritizing champions, to deal magic damage to them. Additional fox-fires that hit the same target will only deal 50% damage.

This attack will help you out later in the game, because of it's AP ratio on the max damage(+0.76 per Ability power)
When combined with your Charm it will be easy to hit all three of them.

Charm
Ahri will blow a kiss that travels in a line in front of her. It will deal magic damage and charm the first enemy it encounters, forcing them to walk harmlessly towards her, while being slowed by 50% for the duration.

I love this attack, and soon you will too.
It's like a taunt without them dealing any damage for 2 seconds, and it makes it really easy for you to hit all of your attacks.
And to make it even better, it has a nice range.
In teamfights make sure you use it on the enemy carry, they won't attack for 2 seconds and your team can easily kill him/her.

Spirit Rush
Ahri dashes towards the cursor and fires essence bolts, dealing magic damage to up to 3 nearby enemies, prioritizing champions. In the next 10 seconds, Spirit Rush can be cast two additional times before going on cooldown. Each enemy can only be hit once per dash.

Your ult can be a life-saver or killer, depending on how you want to use it.
You can use it to escape ganks, chase a running enemy, jump over walls, deal huge damage in a teamfight and so on.
Remember that when this is on cooldown you won't have any escape moves, except for flash.
And her ult costs 100 mana on the first cast, the next 2 casts are free.

I prefer to have Orb of Deception early because it is has the highest damage and the lowest AP ratio, and because of the synergy with her passive.
I max Charm and Fox-Fire after that.
Don't max your charm last, it will greatly affect your ability to hit your combos and gank, because of the cooldown and length.
And ofcourse, level your ult whenever it is possible.

Personal favorites

Greater Mark of Magic Penetration
The only viable reds in my opinion. You need magic penetration for enemies with magic resist runes and masteries. (early game)

Greater Seal of Scaling Mana Regeneration or Greater Seal of Replenishment
You need mana regen. I prefer mana regen per level, because it surpasses the flat ones at level 6 and before that you won't run out of mana that quickly. But you can always go for flat mana regen if you prefer that.

Greater Glyph of Scaling Ability Power
Ability power per level. For that extra damage when you are leveling your W.
It's not that much but you will notice it, trust me.

Greater Quintessence of Ability Power
Flat Ability power. Some early damage can't be wrong, can it? Together with the glyphs it will give you a nice amount of AP.

Optional choices

Greater Seal of Armor or Greater Seal of Defense
If you think you don't need the mana regen, or if you don't have them yet, you can pick armor for some more defense.

Greater Glyph of Magic Resist or Greater Glyph of Scaling Magic Resist
Same as the Seals, if you don't need the AP, or if you don't have them yet, you can pick magic resist for some more defense.

Greater Glyph of Ability Power
If you want the extra damage from the start and not want to wait for it, you can pick these runes.

Greater Glyph of Cooldown Reduction
With 9 of these runes you will have 6% cooldown reduction and with your boots it's 21%.
You will do a bit less damage but you can spam your skills more often.

Greater Glyph of Scaling Cooldown Reduction
Same as the Glyphs of focus but this will give you 8% at level 18. With your boots it's 23%.
Not much of a difference but you can use these if you want.

Greater Quintessence of Health
Flat Health. Gives a total of 78 health from the start. If you want more health you should pick these.

Greater Quintessence of Magic Penetration
Magic penetration. Good choice, early game this can sometimes be more effective than flat AP.
Especially against low magic resist champions.

10-9-11
You probably think that my masteries are weird.
But, if you think about it, they aren't that weird at all.
Ofcourse you can use your own masteries if you want.

You don't have to read this part if you don't want too. It just explains why I use these masteries.

10 Offense

Mental Force 4/4

4 extra ability, not bad.

Summoner's Wrath 1/1

It's not really necessary but you need 1 more point too get cooldown reduction.

Sorcery 4/4

4% cooldown reduction, a bit more cooldown reduction can't be bad at all.

Arcane Knowledge 1/1

10% Magic penetration. That's what we are here for! Because of this mastery we can buy boots of lucidity without having to worry about magic penetration.

9 Defense

Resistance 2/3

and

Hardiness 2/3

4 Armor and Magic resist. For that bit more defense.

Durability 4/4

6 Health per level (108 at level 18). It will give you a bit of health, you won't really notice it without the next mastery though.

Veteran's Scars 1/1

30 Health. 30 more Health at lvl 1, with Durability it is 36 on lvl 1 and 90 at lvl 10. It can safe your life.

11 Utility

Improved Recall 1/1

1 sec less teleport time. Can make a difference in experience, and saved me a few times. (Karthus ult for example)

Expanded Mind 3/3

12 mana per level. More mana for your Archangel's Staff.
You can pick Good Hands if you prefer that though.

Summoner's Insight 1/1

Reduces Flash cooldown by 15 seconds. Especially with the flash nerf a while ago, this can be very good.

Swiftness 3/4

1.5% movement speed. Ahri has a slow base movement speed. This will help a little bit.

Runic Affinity 1/1

Increases the duration of neutral buffs by 20%. If your jungler is kind enough to give you the blue buff you can dominate your lane for a long time.

Transmutation 2/3

2% Spell Vamp. With your passive this will be very useful, you get spell vamp with every attack and after 9 attacks you get even more. This will help your sustain in lane.

Recommended

Flash
Just like your ult it can be used to chase and escape.
Even after the nerf it's, in my opinion, still one of the best summoner spells.

Ignite
Most useful in early and mid game. The damage is really good for when you lack a bit of damage.
Late game it is useful against a fiddle, mundo and all other champs that have attacks that regenerate health.

Good choices

Ghost
If you pick this, pick it instead of flash. I don't say it's better or worse. It's a matter of preference.

Teleport
Really useful to get back in your lane.
Use it too gank lanes by teleporting on wards or chrooms etc.

Cleanse
Really strong spell. It removes ALMOST ALL CC on you. Useful when getting ganked or focused in a teamfight.
Note: It doesn't remove ults like Warwick's Infinite Duress or Malzahar's Nether Grasp

Can be good but not my favorite

Exhaust
Reduces their damage, and with the upgrade in masteries it reduces their armor and magic resist by 10, which will make you deal more damage.

Clarity
If you spam your skills way to much early game this can be really useful to you. But after Rod of Ages and Archangel's it will be useless.

This is just one of the many ways.
I will give you guys some examples of good items and when to get them.

Core

( )

These items will cover everything you need. Cooldown reduction, mana, mana regen, health, AP.

Important items

Rylai's Crystal Scepter
You need this item for health, ap and the slow. The slow will really help you out when chasing .
Note: All 3 Fox-Fires are counted as singe target spells, which means that they slow for 35%.

Rabadon's Deathcap
A must have for all AP carries. The passive is really helpful and it gives a good amount of AP.

Archangel's Staff
Combined with Rod of Ages, which gives a lot of mana, and Rabadon, which gives 30% more AP, this will give you a really good amount of AP. And it will end your mana and mana regen problems.

Will of the Ancients
Really good when combined with your passive, it will give you a total of 55% spell vamp.
I don't get this until very late in the build but you can get it whenever you feel like you need it.

Situational items

Void Staff
When your opponents are stacking magic resistance and you can't kill them anymore.
If you need this buy it instead of Will of the Ancients or Archangel's staff.

Banshee's Veil
When your opponents have a hard nuker that is focusing you every teamfight.
It will save you from a hard nuke and can win teamfights if the opponent messes up.

Hexdrinker
Kinda like Banshee's Veil but this is more for a Karthus ult.

Mejai's Soulstealer
When you get kills as easy as minions. Will give a great amount of AP when fully stacked + more Cooldown Reduction. But you will lose a lot of AP when you die.

Sorcerer's Shoes
If you don't have the Magic penetration runes/masteries. You need magic penetration and this is an easy and cheap way to get it, you have less cooldown reduction though.

Quicksilver Sash
When the enemy has a Malzahar, Warwick, Poppy. That is focusing you.
Unlike Cleanse, it does remove nearly all debuffs including:
Ignite, Children of the Grave, Nether Grasp, Paranoia, Destiny, Infinite Duress, Hemoplague and almost all Damage Over Time abilities ( Poison Trail and Blaze for example).

Note: It will remove the suppression of Nether Grasp but you will still be damaged until leaving it's range.

Note:Remember that Quiksilver Sash does not give you any lingering resistance after use like Cleanse. If you use it to remove a slow/stun/etc, you can immediately be stunned, slowed, suppressed, etc. again.

Farming is really easy for ahri in mid to late game.
But in early game you will have to do it with lasthitting only, and it will take a while until you master Ahri's attack animation.

Here are some tips for farming with your skills.

Orb of Deception is an easy skill to farm with.
You throw it in an incoming minion wave and you will damage them enough to lasthit them or they are already death.

Fox-Fire
Isn't really a farming skill but when combined with your Q it can clear a minion wave pretty fast.

Try not to push too hard in the laning-phase or you will get ganked very fast.
So, lasthitting in early game and use your skills in mid and late game.

You can play Ahri in mid and side lanes, depending on your team.
When you are in mid it is your job to farm, farm, farm and kill
When laning you should be careful when playing against these champs:


More will come soon

Kassadin
I always have a hard time against a Kassadin. His combos really hurt.
I suggest asking your jungler for an early gank so he can't flash away with his ult. When you kill him early you will have the advantage later in the game.
Don't come to close for him too use his Q E combo.

Urgot
I don't see him often but when I see him he is as annoying as always.
The only thing you can do against him is to avoid his Noxian Corrosive Charge.
Don't stand under his tower when he has his ult or he will use it.

LeBlanc
Her nuke is stronger than yours, she can escape your combos with her Distortion.
Wait for her to use her Distortion and attack after the second part of it has been used.
Try to stay out of her range and focus on lasthitting.

Vladimir
He has better sustain than you. And after level 7 you need a really good gank to get him out of the lane. With the recent nerf it is easier but still hard.
Harras him as much as possible before he is level 7 and kill him when it's possible.

Cassiopeia
Be happy that you don't see a good Cass often. Her combo is REALLY deadly.
When she hits you with one of her poisons she can spam her Twin Fang and you are death.
If she hits get out of range as soon as possible. If you are confident that you have a higher damage output you can stay and kill her, but don't run when you get low, because you will die anyway, at least try to take her with you.

More will come soon.

Your job is to focus the enemy squishy champs.
In teamfights you want to stay at the back of your team.
When your tank initiated a fight, and when their CC is used, jump in with your ult and go to the back of the enemy team to kill their squishy champs.

If you get focused from the start of the fight use your ult to get out and get back in as soon as they stopped chasing you.

Play Video

Okay, you are done reading my guide. :D
Try to mix around with the item build so it gets perfect for your playstyle.

The idea of making this guide was in my mind for a long time and now it's finally here.
I hope that it was useful to you, ratings and comments are appreciated.

I won't put all changes in here but only the buffs/nerfs and important bug fixes.

V1.0.0.134:
Spirit Rush:
Cooldown between casts increased to 1 second from 0.75.
Cooldown increased to 110/95/80 seconds from 90/80/70.
V1.0.0.132:
Orb of Deception: mana cost increased to 70/75/80/85/90 from 60/65/70/75/80.
Spirit Rush: cooldown increased to 90/80/70 from 80/70/60.

17-02-2012 Guide Published
17-02-2012 Fixed some spelling mistakes :S and added vid
28-02-2012 Addded Cassiopeia in Laning
06-03-2012 We made it in the top 5!!! TY GUYS :D
17-03-2012 Top 3!!!! :D
18-03-2012 Added scores