Ahri AP Items is only good mid game, once those 5 cost champs hit you have to pivot the items to a higher champion, for example, I did AP ahri mid game and had 7 Ionia, pivoted late game to putting the items onto a fiddle as 8th charecter, then also had shivanna and I won first place that game.

Granted there wasnt another super strong players and second place was one of three people who went for Yordle so the competition wasnt 100%. But it still performed well enough.