Hey there,
My name is Tim and I love to play league. I´ve been playing league since Season 3 and got to Diamond 4 as my highest achievement elo wise. Now i want to present you a guide for my favourite and most played champion, Ahri.

So basically is a burst champion that heavily relies on skillshots. your able to hit your skills Ahri dishes out tons of damage and gives nice cc to her team. She has high mobility from level 6 with her ult and one of the best cc abilitys in the game, her E .

Pros:
-High mobility
-Very high burst
-Has one of the best cc in the game, a 2 second taunt
-Fits into every teamcomp
-Strong throughout the whole game
-Can go in, burst a champ and instantly get out with her ult
Cons:
-kinda squishy
-Can get shut down by assasins like zed, Akali or Syndra
-If locked down by cc in teamfights she will die fast
-Heavily relies on hitting your skillshots

Ahri´s laning phase is very strong. Last hit with auto atacks and try to harass your opponent with your q, orb of deception . save your e if you want to kill your enemy or if your jungler comes to gank. charm can also help you get away from ganks by charming the enemy mid or approaching jungler. your passive helps you survive through poke heavy lanes and is also a great tool to surprise your enemy with a huge heal. keep track of your passive stakcks and use in a big minion wave to get the most healing possible.
Your ultimate, spirit rush is a nice skill to engage or disengage. In some situations you will need to use ahri´s ult to get away but mostly you´ll try to kill the enemy with it. After harrassing your opponent with q and w to around half hp you can go in with your followed by foxfire and 1-2 more charges of your ultimate .Try to dodge as many abilities possible of the enemy mid with your spirit rush while still dishing out your damage.

In the mid game your aim as Ahri is either to kill your lane opponent with your high mobility and damage or roam and help out other lanes. Ahri excels at both so you have to weigh out which gives more to the team. while roaming make sure to keep track of your own midlane opponent and possibly warn your laners of incoming ganks/counterganks. When ganking you should come out of the fog of war with and instantly throw your if it hits it should be a secure kill and if not just proceed with your other skills and try to kill them anyway.
Be careful tho, if you roam too much and don´t get something out of it like a kill or at least an assist for example you will fall behind in xp and the enemy mid can overtake you in the lane.

In the late game teamfights you will have to decide which is the most important target to go on. For example if they have a fed adc you use your ult to get to him as fast as possible and burst him with and your spell rotation.
In a Baron fight for example it also could be very useful to go in and burst their jungler so he isnt able to the baron. Deciding on which target you should go is a tough decision but by playing you will get better at it for sure.
Sometimes it is also very good not to instantly go in as Ahri. works perfectly as a peeling tool for your adc and helps you if your getting chased down. If you land your charm on the enemy engager your team will have enough time to kill that champion and then you can proceed on killing the other champs.
So basically you either instantly go in and burst the target with the highest priority for example a or an or you stay in the back and help bursting their frontline and peeling for your adc.

Against Ap heavy Comps
There are many different item builds possible and you also have to adjust your item build to how the game is going. For example if the enemy ap carry is fed or they have a double ap comp this item build gives you nice survivability and damage. Sometimes you have to get instead of sorcerer´s shoes if they have huge cc abilities like a lissandra ult or a veigar cage



Against Ad heavy Comps
Against Ad heavy comps, for example mid, top and jungle you should rush zhonya´s hourglass and then proceed with your normal build path. If the enemies start to build some magic resistance like or you should buy a Void Staff . Morellomonicon is the cooldown reduction/mana regeneration item to go against ad comps because it is cheaper than and you get more ap. Against ad comps you dont need the mr from the Unholy Grail. Be careful tho, if they have an ap heavy sup like zyra or morg they can damage you very hard despite being just a "support".

Akali
Pre-6 try to harass Akali with and auto attacks. In this matchup you can pick up hybrid pen runes because you want to hurt her with aa´s every time she goes up to last hit minions. Post-6 the lane gets difficult. Akali can easily burst you with Mark of the Assassin , Crescent Slash and her ult Shadow Dance. Try to last hit and harrass her at the same time with your q. Once she is onto you with her ult you most likely have to use your ult to gain distance. Then kite backwards with your e, w and q.
If you hit your e you should be able to kill her instead of her killing you. Your e is your most important skill in this matchup. be careful of throwing it tho because with the speed buff and invisibility of her w Twilight Shroud she can dodge it easily and then you have to just run/ult away.

Anivia
Pre-6 the matchup is yours. Anivia has a relatively low auto attack range which helps you harrass her with and auto attacks. Ping the jungler for ganks so you are able to kill her despite having her passive Rebirth up. Junglers like Jarvan IV or Lee Sin excel at killing anivia early on. Post-6 the matchup gets tricky. Her burst combo of Glacial Storm and Frostbite shreds you instantly and you cant dodge the damage. Try to stay out of range of her ult and farm safely with if you harrassed her down to 3/4 or 1/2 of her hp you can go all in. Make sure to dodge her q . So basically this matchup can go both ways but you should be able to get a little lead in the early game and extend this lead. Together with a good jungler you can destroy Anivia with your high mobility because she doesnt have a real escape mechanism.
Annie
The Annie matchup is a very snowbally lane. Pre-6 you are in the favor especially because your q has a higher range than her q Disintegrate and she´ll most likely be using the skill for farming. When has her Passive Pyromania up you need to be careful, especially Post-6! Before 6 she shouldn´t be able to kill you but Post-6 she can instantly burst you with her combo. Make sure to stay out of her Tibbers range and farm with your q. Try to dodge her Summon: Tibbers with your ult, then she lacks a lot of damage. Advanced players will be able to completely negate her Tibbers with a prefectly timed
Zhonya's Hourglass. Use your Range Advantage to it´s best and you should be able to win this matchup. Often you can hit a straight because she wants to get in stun range.
Azir
Azir is an exotic champion. He was pretty weak and bugged for quite some time but since people acutally learned him quite well and started to understand the champion he can be very strong. Keep track of the amount of soldiers Arise! he has up. If he has one soldier his damage is not that high but with the levels he can dish out tons of damage in just a few auto attacks and his q Conquering Sands. With the new patch azir is able to travel a longer distance with his e because he can combine e and q together. in the early stages of the game you can outclass him definetely but be careful in late. His ult Emperor's Divide is also able to block your ult so he can block your movement and high mobility.
Brand
Brand isn´t played too often in the current meta but he´s still a powerful champ so don´t underestimate him. Pre-6 he can harass you pretty easily with his w Pillar of Flame and follow with his e Conflagration. Try to dodge his w with smart movement because it is his main damage skill. If you want you can take Movement Speed Quints in this matchup to dodge his skills easier. Starting with flask cristalline flask is also an option to counter his easy harrass. However you can still get the upper hand in the early game if you play it smart. Post-6 you got the upper hand. Try not to get harrassed too hard and poke him with your and if you feel like you can all-in him do so. Use ur quick movement of the ult to dodge his stun and make sure to hit your e which shouldn´t be a problem tho because he doesn´t have any escapes. Be careful of his burst! If he gets a few items for example Liandrys Torment and Rylai´s Cristal Scepter he hits very hard. So basically use your mobility advantage to dodge his stun and burst him with your combo then, just be careful of his dmg when he has ignite up.
Cassiopeia
Cassiopeia is a lane bully. Since her recent changes her q Noxious Blast doesn´t hit that hard anymore in the early game. You win this lane by dodging her so she can´t use her e on you with the 0.5 sec cooldown ( Twin Fang ). If you want you can pick up movement speed quints but i don´t feel like it´s a must have. This matchup should be yours Pre-6 and Post-6. At level 6 your kill potential is even bigger because of your ult . Dodging her ult Petrifying Gaze with yours is very important. It shouldn´t be too hard tho because her ult has a slight cast animation and cast time so you can ult to the right, left or the back to juke it out. Be careful of flash ulting at you, especially in teamfights.
Diana
Diana´s kit is built around assassinating enemies and still being quite tanky through her ap-scaling shield Pale Cascade. Pre-6 you definetely have the upper hand. Diana is melee so you should try to harass her with auto attacks whenever she walks up to pick up farm. If your doing it right she´ll be forced to last hit with her Q Crescent Strike which will cost a lot of mana. Especially when you have 2-3 points in your Q it will hit her quite hard and you can either force her out of the lane or kill her. Post-6 the matchup gets kinda tricky because she can insta kill you, be careful! She will try to do 2 auto attacks to stack her passive up
,then Q you and go in with her ultimate Lunar Rush. Especially when she can attack you with her passive auto attack Moonsilver Blade she hits you very hard. What you wanna do is position so her q doesn´t hit you. Try to farm with your orb of deception and auto attacks from the highest range possible. If she manages to hit the q you have to back up quickly. If she is still able to jump on you you should ult backwards, charm her and unleash your combo. If your able to hit your Charm you should be able to kill her with your + Combo. So basicall you have to avoid Diana´s q to be able to win this matchup, both champs have huge kill potential but if you manage to kite backwards with your ult and skills you should be able to win this matchup. Especially in late game you can f*ck up if you hit your e because she has zero escapes.
Fizz
Fizz is one of the hardest Champs to play against as Ahri. If he times his E Playful / Trickster he can dodge a lot of your damage especially your taunt and then he can burst you very hard. Pre-6 you have to build a lead as big as possible. He´s melee so auto atack him every time he comes up to take farm and try to poke him down with your Q . Be careful of his level 3 tho ! His W active Seastone Trident combined with an ignite deals a lot of damage over time. You win this matchup if your able to track the cooldown of his e because if he uses it to farm or dodge a skill of you it´s your time to go in. His E cooldown in the early game is quite high so use this to your advantage. Post-6 the matchup gets very difficult. Even if you outfarm him and have a kill or two he can still kill you pretty easily. Play the lane very safe from now on. Farm with your Q so he will be forced to use his E to go in and not dodge skills of you.
Don´t hesitate to use your ult to dodge his E damage and reposition yourself, also try to dodge his
ult Chum the Waters with yours. If he manages to get on you ult away if you feel like it´s necessary and kite backwards with E and W. Just make sure to not give him easy kills because fizz is a snowball champ and if he doesn´t get fed he isn´t that useful. Make sure to warn your sidelanes if he´s roaming and follow him but be careful of him just baiting a gank and waiting in a bush in the jungle to burst you.

Here is a great example of how you can dominate your enemies and completely crush them with Ahri.(not my video, just an example of a very good ahri player) Play Video

Longer in depth descriptions of champion match-ups will be coming soon. I am working on these. Until then i hope my short tips at the top will help.
Thank you for reading my guide and have fun playing and destroying enemies with Ahri!
Make sure to leave a rating if you liked the guide and if you dont like something let me know, this is my first guide.
Greetings, timeeGER