Welcome to my first serious build on Mobafire, describing how I play my main, Ahri.
I don't have too much experience with making builds from before, but bare with me, haha. :P
Ahri is not too bursty unless you get your full E-Q-W combo onto your opponents relatively early, when they don't have too much Magic Resist. She is more of a "I am going to kite you around and deal constant damage to you while I do so" champion.

She has great survivablity when her ultimate, Spirit Rush, is up, but if she does not have it up, almost any champ with level 2 boots can chase her down due to her low base movement speed.

Essence Theft is Ahri's passive. every time she hits an enemy with an ability, she gains a stack (max 3 per ability cast). when she has 9 stacks, her next ability will grant her a bonus of 35% spellvamp. this greatly enchants her early sustain in lane. It's a great passive early game, it drops off a little bit late game, but it still has some meaning to it. you should try to hit as many enemies as possible on the 9'th stack with Orb of Deception to make the most of this great passive.

Orb of Deception is Ahri's Q. Going out, the orb deals magic damage, on the way back, it deals true damage. the true damage really helps if your lane opponent is stacking mr.
It's a skillshot, very quite similar to Sivir's Boomerang Blade in the way that it returns.

Fox-Fire is Ahri's W. She releases 3 fox fires, auto targeting the closest enemies (prioritizes enemy champions). If an enemy is targeted by multiple fires, they deal 50% less damage. I level Fox-Fire up first. The reason is: it is a secure source of damage, and it has the same mana cost from level 1-5. Fox-Fire is great combined with Rylai's Crystal Scepter and Spirit Rush.

Charm is Ahri's E. She blows a kiss, taunting any minion or champion hit. You want to use this to immobilize damage dealers in teamfights, and for being sure to land both Orb of Deception and Fox-Fire in a brutal combo, and for chasing down runners combined with Spirit Rush.

Spirit Rush is Ahri's ultimate. She dashes to your cursor, sending out 3 Essence bolts, dealing magic damage to any enemies targeted (prioritizes champions). You should use this for either: Tower diving, escaping, chasing down runners or changing position to land your Charm into your combo. When Spirit Rush is up, Ahri can escape nearly anything unless taunted.

Pros:
+ Absolutely amazing ganker.
+ Can both burst and deal sustained damage.
+ Nice CC with her Charm.
+ Can chase very well with Spirit Rush.
+ Her auto attack animation is very fluid, so she can last hit with ease.

Cons:
- Squishy!
- Low escapability if Spirit Rush is on cooldown.
- Requires a lot of farm to do well.
- She has 2 skillshots, so she takes some time to master.
- Ahri is quite mana hungry, and goes OOM if you are too agresssive early.

Reccomended Summoner Spells:

Flash is a nice skill on Ahri. before level 6, when she has not yet gotten Spirit Rush, she can Flash into Charm if the jungler is coming in for a gank.

No description needed. Ignite is usefull on almost any champion.

Other Summoner Spells you can use:

Ghost gives you some extra mobility combined with the 3 flashes from Spirit Rush, so it's not a bad pick, but I do reccomend flash more.

Exhaust helps you keep up with quick enemies if you can tag them with it, but you don't really need it considering you have your high-mobility ultimate.

If Spirit Rush is down, and you get ganked by, say, Rammus, you csn just cleanse that taunt. altso helpfull if laning vs. a high CC opponent like Malzahar or Lux

Clarity is not really too Reccomended by me. if you can avoid spamming your abilities, and being too agressive too early. You can take it if you want to, be my guest.

That about rounds it up. Feel free to Vote of leave a comment. I really did put effort into this, and please don't be to harsh, this was my first real guide, haha :P