Ahri is not even close to overpowered, especially compared to other assassin-like champions such as Shaco. Ahri can't really even fit into the AP carry category either, other AP carries just outscale her. Finally, she isn't much of a support, all she can do is sit back and throw orb of deception and Charm. Orb of Deception's speed should be buffed, at least on it's return speed. Fox Fire needs a small nerf on it's base damage, and Charm is fine. Her ult is her only way of getting out of fights, she has no other means of escaping. Hope this helped.