I wouldn't invest in a Rylai's Crystal Scepter because only your Q ability benefits from the slow. The ultimate would but they are dancing while they are slowed.
You might want to get a Mana manipulator if you are in a lane with another magic user and build it into a Soul Shroud, since she is an aura champion.

FYI this is just me messing alround in acouple of games i didnt do bad during the 5 test games but then again enemey team sucked nuts, if i would use this char in a ranked match i would build way more surrport and less AP