Pros
Great Damage Output
Great Mobility with her Ultimate
Using her combo, she can heavily damage or kill tanks or tankier people

Cons
Very Squishy
Without her Ultimate, Low Mobility
Charm can be hard to hit

The Summoner Spells I take with ahri are teleport and ignite. I believe teleport is a must for ap carries or mids, because these people are normally slow, and it provides great mobiltiy across the map. I took ignite because when you just need to secure a kill, but dont want to tower dive, ignite comes in handy. Other viable spells include: Cleanse, Flash, Exhast, and Heal. Cleanse is great for Ahri because again, she is slow, she only moves 375 with her full boots, so she is subject to a lot of CC, and works perfectly against a CC machine such as Nautilus. Flash is an all around good spell, can be used to escape, (although for ahri, she has "other" means of escape) or can be used to set up a charm. Exhaust, this spell is good when your jungler comes to gank, or if you need to land a charm, that is if you suck at aiming it. Heal, its a good early game/mid game refresh for tough spots, but will rarley be used late game. WARNING: DO NOT TAKE CLARITY AS AHRI!!!!! Ahri is not someone like karma who can run through mana quickly. She isn't a spammer, you should not be using your q a lot on minions. Clarity is a waste for Ahri if you know how to play smart, and it can be used to fill with a more usefull spell like flash or ignite.

When the game starts, I normally starts off with an amplyfying tome and a health pot. From there I get boots of speed and finish off a fiendish codex and magic penetration boots. Next, i finish off Morello's Evil Tome and start my Rabadons. I get a Morello's first because it has everything an ap needs, cooldown reduction, ability power, and mana regeneration. It also comes with a nice active ability. A Rabadons is NECESSARY for any ap. It gives you a ton of ap and increase your abilty power by 30 percent. So your mid game build should look like a Morello's Evil Tome, Magic Pen. Boots, and depending on how well your doing and your CS, a Rabadons or partially built Rabadons. From here, I go after a Rylai's Crystal Scepter. For 3 reasons, 1. the ap it gives 2. the health, because i like to at least partially survive a ranged ability as ahri, and 3. its slowing passive. This becomes very usefull when you cant get in range to hit charm, use your orb of deception to slow them and then hit charm. After Rylai's, i go after an Athene's. This is a disputable item for me. I get it because of the massive mana regen, which allows you to spam more. It serves as your own permanent blue buff, and eliminates the need for clarity. It also comes with a decent amount of abiltiy power, magic resist, and cooldown reduction. Again, if you play smart, you dont need this because you dont spam. So an Athens can be replaced with a WOTA, Abyssal Scepter, or Zhonya's Hourglass. Fianlly, i finish up with a void staff, because its another ap boost, it comes with a decent amount of ap and give you 40 percent magic pen. which is usefull to do more damage to tanks. I normally do not get a WOTA on Ahir because of her passive, but it would be helpful and can easily replace an Athene's. Now for teams that have a lot of AD or AP, build accordingling. Either drop the void staff or athenes, and get an abyssal for ap teams or zhonyas for ad teams.

I up Orb of Deception by level 9, how most ahri players do, foxfire by level 13, and charm by level 18, and obviously like any ultimate, up it when available at levels 6, 11, and 16. Now this is how ahri works, if you land charm, the opponet should die, unless theyre tanky. The Combo you need to use is E-Q-W-R to wrap up. If they are tanky, then the E-Q-W combo will need to be used 1 to 2 more times. So if you land charm, they enemy should be dead. Now charm is pretty easy to hit, but lets say your oppenent is always behind minions or runs zigzag, or you suck at hitting it. use other things to land your charm. your ultimate is good, and flash too. Charm is also the perfect initiator to a team fight. If you land it, then you have a defenseless enemy walking toward your team!!! its great for turning that 5v5 into a 4v5. Now on to your ultimate, this ultimate is special because people like to use it differently. This is my advice. DO NOT immediatly use up all 3 stacks. YOu should use 1 for damage, and keep the 2 for a chase or if the battle goes wrong and you need to escape. Don't be afraid to use your ultimate in a team fight.