Good Ahri build? Suggestions?
24/0/6 masteries. Runes are sketchy because I only have a few.
24/0/6 masteries. Runes are sketchy because I only have a few.
I usually rush out chalice of harmony so I can stay in lane longer. I find that it's ok to build AP more slowly with Ahri, if only because her scaling is so low -- 20-30% for all abilities. I start with 2 faerie charms and get boots as soon as I can after that -- she also has very low move speed so you need to help her a lot until you get your ult.
I also build lichbane, so I agree with that. After Sheen, I usually start Zhonya's Hourglass by building the Seeker's Armguard. Finish Lichbane and then wait the long haul for Needlessly Large Rod. I do Zhonya's because, if you're like me and play agressive Ahri, your ult will generally land you in dangerous places -- I've used ult to chase enemies past their tower. So in these cases, Zhonya's can save your life. Also, you have rather low HP, so if a bursty champ comes to gank, it will again save your life.
I recommend any mage, especially one who is facing off against another mage, build Abyssal Sceptre. It adds AP, MR, and applies an MR reduction on nearby enemies.
Those are my suggestions. Take them as you will.
Thank you. How would you build against a talon lane?
Grab a seeker's armguard for early defense 
Agreed. Any Armor you can get early will help you survive against Talon.
EDIT: OMG, especially if his current change goes live. He'll be even burstier if his Cutthroat slows instead of silences since his passive bonus damage triggers off of impaired movement. He'll be able to get bonus damage on both directions for rake and could lead with Q for bonus damage and perhaps end with Q for a full-on 100/0 effect :(
For Talon. Hmm.
He's AD and very mobile so you'll want to emphasize your mobility and armor. This supports getting boots early - I always use Sorcerer's Shoes for the magic penetration (can't go wrong with magic pen). This way you can more easily dodge Rake without having to burn flash. This also supports building Zhonya's as that item provides like 50 points of armor. I would highly recommend grabbing Glacial Shroud
as this provides both mana and armor and therefore will let you stay in lane. If you go with Shroud, I recommend going to Frozen Heart
for the armor, you could instead go for the Iceborn Gauntlet
and it's not a terrible idea, but it only provides 60 armor as compared to the Frozen Heart's 100. Then you could still put Sheen to use.
Rylai's Crystal Sceptre will give you slows on your abilites, which is great versus highly mobile opponents.
After that it's all mechanics and control. Make sure you're frequently using orb of deception on the minion waves both to get cs and to proc your passive, which heals you. Be sure to be constantly moving and prepared to dodge Rake. Cutthroat is a point-and-click ability so you can't dodge that one -- stay near your minions so they aggro on him if he uses cutthroat on you. try and hit him with Charm when he's near your minions/tower. Be ready to ult or flash if he ults, you do not want to get hit by all those blades and have him positioned between you and your turret.
I use a rune page of Magic Pen Marks, Mana Regen Seals, AP Glyphs andAP Quints. I find this rune setup suits most mages well and it's been my standard for years. The builds are totally up to you but I've seen a lot of people using Rylai's over Lich Bane for the slow effect and bonus HP.
Will keep that in mind.
You have no mana regen item, and twin shadows is pretty unusual (you can probably use it, but for the most part I only see the item on supports who use the active for vision). I've only ever seen Shiphtur buy Lich Bane
I usually see Ahri's go two ways, either Athene's -> Deathcap and just play as a ranged mage with good waveclear and some assassination potential, but probably need to rely more on poke before all inning (unless you have insane mechanics and can land all your spells, or are just really ahead), or DFG rush -> Void Staff/Deathcap, where the goal here is to be able to 100 - 0 pretty much anyone. The former allows you to have more sustained pressure, since you have a lot more mana regen and CDR so you can deal more damage consistently, where the latter allows you to have short moments of very high pressure, where you can delete players, but will probably have trouble staying in lane for long periods without blue buff or very careful mana management.
I would consult Probuilds for more tips, and watch some VoDs of pro players streams
Hope this helps