I like it, but get Madred´s instead of Black Cleaver and maybe Frozen Mallet for Phantom Dancer. Bloodthirster would also work better cause of livesteal. Take Malady out.
And your runes aren´t choosen well. U don´t need manareg and maybe some speedrunes and as-runes for the Greater Marks of Desolation.
This way u would make BIG DMG without much ap or ad^^ Madred´s + Wit´s End + Sword of the Divine + your passive e-skill = big magic dmg ...even tanks fall easily ;)
That´s the way i play her it works much better that pure AD or AP. I hope i could help u^^

when against some ninjas/non-mana users i switch my wits end to a last whisper, for the armor pen, also when im against a tank heavy team. and late game i trade the malady for the starks since there are more team fights and potential to use the aura

Maybe I should add Zeal -> Phantom Dancer earlier, but I think i'd have a problem with the killing potential. I mean Items such as SoTD, Wit's End, and Malady really benefits from the attackspeed, paired with Stacked Deck + Pick a Card it becomes a real killer, all with 60ArP from SotD's activate and my natrual with runes. -> Don't forget The Black Cleaver as well.