What about making Kallista's Rend Stacks, like Vayne's Silver Tip arrows?
Where if she attacks another target, the stacks will disappear. That way, they can keep her infinite stack on objectives and discourage the buy of a Runann's.
Because come on, Vayne and Kallista are really similar. Kallista is sworn by a person to hunt down someone for Revenge. Vayne hunts down evil doers. So why would someone who is hunting down another get to throw spears at everyone, and not just her Target. Logic.
