So, heres one easy way to balance Kalista

Now has a second Passive: Movement speed slow additionally slow Kalista's Attack Speed by half the amount that they are listed at.

E now caps at 15 stacks.

Bam, now Kalista is balanced; she can be caught if you have a slow on her and she can't attack something for 3 years and then do 10000 burst damage to it with E.

Too bad Riot won't ever read this. Or even if they did, their is 0 way that they would implement it or even talk about it. The LC$ Mobility Master Race is here, and Rito is making sure that they will never go anywhere.