Hi guys, this is my first time doing a full out guide instead of just posting builds. I decided to use ahri because I found this build very useful and got me plenty of kills. Ive heard a lot of people saying she is underpowered but i disagree with that. Ahri is a great assasin. Her ult grants great mobility and when you throw ghost into the mix, you are almost ungankabale. She does a fair amount of damage.

Pros

Good early game damage
High Mobility (due to ult)
Does true damage
Her ult attacks 3 people
Skill Shots (can go through fog of war)

Cons

Squishy
Really vulnerable to CC
Need to be good at skill shots
Some people can counter her ult (Kassadin, Akali, etc.)

I see a lot of people using flash on her, which i Personally think is wrong.
Her ULTIMATE is basically 3 FLASHES with a minute cooldown.
I found Ghost to be a much better choice. Still provides good speed for chasing and running away. When you ult fails against champions such as akali and kassadin, just use the spell to run.

Ignite is a great choice to last hit opponents who are always just too lucky.

The ring provides an all round good choice for all mages. Ahri is an assassin who is also a mage. AHRI is very mana hungry when you spam her spells.

Sorc shoes - She does magic damage, so i find she could use the extra penetration to her spells. Ionian boots are also a viable choice, but I prefer Sorcerer shoes.

Rabadons - Gives a nifty amount of AP

Rylais - Ive seen a lot of people debate this with RoA, but I prefer Rylais. I know ahri is mana hungry, but an early game sheen should help with that. Also, try to grab blue buff if your jungler allows it.

WoTA - Gives nice spell vamp, and revolver helps ahri sustain herself early game.

Hourglass - You can choose this when you are fed late game. Gives a nice passive in those tigh pinches where your spell cooldowns seem to take forever. You can choose a defensive item over this if you want to.

Grab a ring and go to a lane. When you lane try not to spam your spells as much. Just last hit and wait for ganks. B when you have enough for a pair of boots, and a revolver. keep farming until you get sheen where you will be able to spam spells more. You should have 1-2 kills and 0 deaths by now if your jungler ganks and you saved your mana for those moments. You should have pushed/been pushed your lanes turrets by now. Start buildin for a rabadons and try to gank. Ahri has great ganking potential so its should be easy to get kills when ganking. In teamfights never initiate and come in half/two thirds through teamfights. The CC era in the teamfight should be over and you should be able to rape all the carries by now. Due to her ult AHRI can catch up with almost anyone when they try to run away. Keep doing this in teamfights and you should be able to get kills and be acing the other team (If you have a decent team).

Ahri is very mana hungry early game, so when you spam your spells for your passive, you wont get much out of it, because you will barely be able to use it due to being oom. This is why i recommend a revvolver so ahri can sustain herself with EVERY spell she uses.

Please try this build out before rating. Hopefully it was helpful. Since this is my first guide, I could use some helpful comments if you found holes in this build. Please tell me on the comments and ill give feedback and try to change my guide accordingly.