Syndra buff idea (casting Q on another Q makes it bigger)

So if she casts Dark Sphere and then casts another one on top of it, both energies combine and form a bigger sphere. The 6 second timer is reset so you can still manipulate it.

If you throw the sphere with W, it deals more damage and slows more heavily

If you push the sphere with E, it deals more damage and knocks champions aside rather than stunning them. Or maybe both. Take your pick.

Bigger spheres don't do anything for her ultimate

Syndra can only increase the size of a sphere once and reset the timer of a sphere once as well.