This build is only tested at a lower level against comp players with Ahri up top, but I hope a higher level player will try it somewhere and give feedback.

My idea has a foundation in some quick math I did to see how fast ahri could kill a permastunned nunu without dodges resist or interference. An unlikely event but I found that, early game, stinger could be, in an unlikely scenario, over twice as effective as a Rabadon's cap and can build into an item that gives 65 AP and 25% cooldown.

The idea is simple, build AD ahri until level 6 and take advantage of her range and rune/mastery based AD power which has the greatest impact in the early game before higher tier items are purchased. Then, once in possession of both stinger and boots of speed, begin a pure AP build.

Dagger, according to the permastunned nunu math test I did, builds AD a bit less effectively than a Doran's blade or long sword but it builds into stinger which is the first target of this build. From that point on I just posted the items I've had the most success with.

It may just be me but Medjai's Soulstealer and Ahri just seem made for each other.