So, in my opinion, Taliyah is somewhat weak if you compare her to others.
I'll try to keep it as simple as possible.
First of all: Q
Her Q is fine, except on the enchanted ground. What if instead she would throw 1/1/2/2/3 rocks depending on the skill level (When she's on the reworked ground)? But lowering the damage so that it wouldn't be considered op, or just remove the half mana cost.
This skill is interesting, but really hard to land. What if with each level, we would increase the AoE width? It should be compensated by something so that it wouldn't be op, but I have no idea what.
Her E and R are fine the way it is.
Also, I think it's a bug (or maybe it's ment to be like that?), but Taliyah can't use her E right after using W, which makes the combo a lot harder to land..
These are just my ideas.