SO i enjoy playing Ahri a lot i have actually added her to my favorites list :D. Anyways this is my build for her if you like feel free to comment but try to respect other and not be rude.

For runes i take Mark of Magic Penetration for the spell pen. of coarse. Next is Seal of Scaling Mana Regeneration for mana regen per level, now i find with these she has barely any mana problems like if you are dying in lane and need to spam spells for her Essence Theft just hug your turret and you should regenerate mana pretty fast. Next is Glyph of Scaling Ability Power for AP per level, i entered a match once and someone was free picking her and they had no mana (they started with boots) so i out laned them with my extra AP. For Quints i take Quintessence of Ability Power for the flat potency at level one so this also helps a lot.

For masteries i go 21/0/9 with four in Mental Force instead of 3 with one in Summoner's Wrath ,i do not get the buff from Summoner's Wrath in the offensive mastery tree because it does not give a whole lot of AP while on cool down but if you prefer that then by all means take one point out of Mental Force and put it into Summoner's Wrath . The rest of the masteries in the offensive tree are the standard AP masteries. For utility i get 3 in Expanded Mind 1 in Summoner's Insight 3 in Meditation and 2 in Swiftness i get 2 in swiftness because i hate being slow and i find that my jungler's are usually selfish and do not give the mage on the team the blue buff and with my luck the enemy team has theirs already but if you are confident in your jungler feel free to get Runic Affinity .

I start with the Doran's Ring which is pretty standard for Ahri but i do see people get Boots if you prefer. Okay now i sometimes see people get 3 Doran's Rings but i find she only needs one, so instead i get Sorcerer's Shoes usually i try to get it first back but sometimes i have to back and end up getting Boots and maybe some Health Potion. Next is Rod of Ages and Hextech Revolver. After i get the Revolver i usually get Needlessly Large Rod but if you want you can finish your Will of the Ancients. Either way i do not finish Rabadon's Deathcap before the Will, i find i do not usually need it any earlier than that. After Rabadon's i get Rylai's Crystal Scepter i start with the most expensive piece first, the Giant's Belt, but you can start with less expensive pieces if you want. After that it can differ, i usually get Morello's Evil Tome but if you are having some defense problems get a defense item instead like Abyssal Mask or Zhonya's Hourglass or if it gets really bad Thornmail or Force of Natuere.

So the skill sequence is pretty simple, i get Orb of Deception at level one and max it first, Charm at 2 and leave it for the last few levels, and Foxe Fire at 4 and max it after Orb of Deception. Now for the ultimate it is fairly simple just get it whenever you can, Spirit Rush is a great spell for chasing and running, usually if i overextend i am not worried as long as i have my ultimate up and if i have that and flash i am totally fine.

For summoner spells i use Ignite and Flash, both are very easy to understand. Ignite does a good amount of damage and if your ult just barely lets them live Ignite should finish the job, and if you decide to put the one point in Summoner's Wrath then you will get 5 extra ability power while Ignite is on cool down. Now for Flash i like it over Ghost although i have seen some people run Ghost but i personally prefer Flash for a number of different reasons. First off it gives you a great chase, and added with [[Ahri]'s ultimate i find that i can almost always keep up with people.This spell also works as an escape allowing you to jump over wall or get that last bit of distance from your turret out of the way, and again add this with her ult and you can be almost unchasable.

Ahri is great in team fights because she has 3 AOES and Charm which i have found has turned the tide on team fights many times. Just Charm their tanks away from the fights and let your team beat on them. Her Orb of Deception, Fox Fire, and Spirit Rush all do AOE damage and with the Will of the Ancients she gives surrounding teammates spell vamp which can also help a lot in team fights. Keep in mind even with the tanky items i have here she can still be quit squishy, and if you are doing well they might focus you in a team fight so be cautious!

So in conclusion Ahri is a great champion and she is way fun but some of her spells are skill shot's so that might be hard to learn and her ultimate is a "to the cursor" spell meaning when her ult. is used she will jump to where your mouse is. So just keep practicing and go ahead and try your own builds if this one does not work, again feel free to comment but remember to be polite to others.