User blog comment:KarasuGamma/Ahri's Nonexistent Role/@comment-7658432-20130410045747/@comment-7658432-20130410153702

^ This.

Rushing RoA on Ahri gives her extra health for one on one fights or teamfights and extra mana to effectively launch her 3 skills for harassing without loosing too much mana. The AP that comes with RoA is also welcomed. So you brought yourself a sustaining early game item in which you benefit from all of the stats it gives. Try building it after getting 2 doran's and boots. Effective HP, MP and AP to towerdive/kill/gank.

Also, any AP Carries could use the extra durability that RoA provides excluding manaless champs who usually have escape mechanisms.

Noticed my build? Full of HP and Utility. That's Ahri's role. Bringing too much utility not damage. The damage part is just a reward after hitting your utility skill (Charm). Land Charm then enjoy the skills empowered by Rylai and Liandry. That's all the damage you need since you can simply cast your skills all over again. It also removes the uncertainty to use Spirit Rush during clash because you can survive teamfights.

Conclusion: Ahri would make use of RoA for sustain and durability.

Note: Assassins always welcome extra health.