Why do you feel that she is unrewarding?
She isn't a high risk champion afaik, just has the option to take some.
R needs love, agreed. Maybe give more damage if she lands it correctly and less if she fails, and fix that bug where people sometimes dont get ulted if they stand too close to you.
Passive is actually cruical so you have to buy only one mana item, Without it e spam would be impossible without more mana items and blue buff.
1 basic q e rotation at lvl 3(1 point in q, 2 in e) costs
35 + 3 x 60 = 215 mana
at lvl 3 you have 400 mana, it takes more than half of it up.
Why would you ever buy chalice on Cassiopeia ?
I feel most of those things will be changed in the rework(ult will deal less damage tho T.T)