Kalista Needs a New Passive, Urgently.
Short overview of my history with Kalista: Played her a smidge around release (Nothing crazy, maybe 5-10 games), but stopped playing her because of her passive being awkward to handle. Everyone and their Season 1 ancestors all predicted she would be a professional nightmare due to her passive, which was spot-on. Picked practically every game for a while in pros before she got nerfed consistently over and over to the point of being gutted. Fast forward to late-/post-Season 6, I finally pick her up again and find her really fun to play because of her unique playstyle, especially with her on-hit synergy.
I feel like Kalista's biggest problem is that her dash-passive is ridiculous. It's clearly broken beyond belief, a nightmare to play against if the Kalista is good. (I'm definitely not with her) It's so ridiculous that Riot nerfed her so that she is currently the only character in LoL with a 0.9/1 (AKA: 90%) AD scaling on her autoattacks.
Thematically, her passive makes some sense, the Spirit of Vengeance dashes over and over after her mark. It's kind of cool.
When implemented into gameplay, however, it's just bonkers. There is so much power budget assigned to it that much has to be removed from her kit just to make room. (Only somewhat recently, she got a compensation buff to gain AS while close to her Oathsworn.)
My suggestion on a new passive: Give her back her 1-1 scaling autos, remove the dashing entirely (and fix the autoattack windup to compensate), and give her and/or her Oathsworn +Movespeed for proccing her Sentinel Mark. This allows her to keep her theme of chasing down targets, as well as encourage better teamwork among her and her bond.