A Kalista Nerf
Change her passive so that her 'hop' in between basic attacks can only be done every 4 seconds or after a Q is thrown. Every point in her Ult could lower it by 1 second.
The whole 'stacking aspd and perpetually moving and attacking' thing is part of what makes her inappropriately-difficult to play against. By forcing intervals which she can't hop, you remedy this completely. The strategic Q-hop, working against this passive, would allow her to keep a bit of that escape potency.