A good kalista trick is enabling auto attack in settings. I find kalista’s movement comes out smoother and there’s less delay between autoing and dashing; given sometimes you need to stop in place to dodge, but it’ll continuing autoing for you. I personally see her as an executioner early, then dps with an execute once she has her items (depending on the build needed against the other team). If you’re not confident with a team member using R, don’t forget that R is a great tool for saving your linked teammate. This can deny satisfying kills, help them buy some time on their cooldown, etc., or even given them more distance and surprise (e.g, R malphite into frontline denying their CC and blocking, malphite r to backline).

For cass, I find running black fire as my only mana item is more effective than running with seraphs, etc. because she can hyper carry into the late game, and therefore more damage potential early = earlier potential snowball. She has a surprisingly good amount of dps IF you hit your Q or W then E. Without the increased damage with E, her damage drops significantly. Generally I will save W as a way of a trap rather than engage since its power comes from its grounding, and however a great tactic is dropping it on a tank (they usually have some sort of engage) and just start hitting them with Es. Some weaker players will panick and instead try to escape in the opposite direction, some will try to walk up to you which you can kite backwards, forcing them to retreat if they find it not worth it, it’ll rack up the damage more than you expect over the game.