My Problems With Kalista
Her passive is pretty overpowered because melee champs can't touch her. Nothing like being able to infinitely kite backwards with no cost to you. It should at least have a short cooldown, or activate after a certain number of auto attacks like diana's passive.
Her ult is probably the most useless thing since draven's passive. I understand the idea of binding yourself to a single champion so that together you become more powerful, but it forces her to play in a duo lane. Let's say the person she is laning with disconnects or just leaves the game. Now not only is your soul bound less effective your ultimate is completely useless. I think that her ultimate should do the same thing it does now, but instead your able to use it on any of your friendly champs and it switches the person your bound to to that champ. This way she can be played in roles other than adc or support, and it gives her more versatility in team fights. For example she ults the friendly rengar who then gets thrown forward, and he then ults and jumps onto a fleeing enemy or enemy who was originally to far away for him to quickly jump to.
The passive on her W is okay, but once again if your bound ally disconnects or just leaves the game it is useless. I think it should be changed so that when the sentinel sees an enemy champ it chases after them and latches onto them applying a mark. This mark can then be activated by Kalista or by her bound teammate and it will do initial damage based off of Kalista's ad or ap or whatever and then cause Kalista and her bound teammate to do bonus damage to the enemy champion for a short time. This would allow the sentinels to not only be used to scout areas where you have no vision, but also offensively (like during teamfights). However, the problem with changing it in this way wouldn't necessarily allow her and her bound teammate to focus damage onto the champion they need to. So maybe keep the passive on w the same, but let the sentinels apply a mark that does damage based on Kalistas stats that can be activated by her or her bound teammate.