2 idea's to limit kalista.

Martial Poise has a 1.25 second static cooldown timer meaning that she can not jump after every attack but after every second or third attack . When her passive is on cooldown she can cancel her attack animation. It is a fun design but currently it is just way to impossible for any melee to stick to her when she is jumping twice a second late game.

Rend max damage to neutral monsters capped at 750. There is no reason that something should be able to out smite smite by 1000+ damage. Yes I have seen kalistas E do 2500 damage to baron.