As a Kalista player, I admit that it can be har5d to time or make anything work with your support if you aren't talking in skype or at least doing a duo with a friend but it isn't entirely immpossible. But just because it's possible doesn't mean it can't end badly, there have been times when my support launched to wrong direction by accident or I timed the ult wron, but for the most part I use her ult to save my supp so he/she doesn't diewhen there's a chance of both oof us making it out alive and play a defensive ult. There are still times where i use it offensively but I mostly prefer it to save my oathsworn's life since it's also easier to time and all than when you are trying to go on the offensive to get a kill though it's still hard to pull off when you don't have enough communication. Also, AFK supports after the time limit to take back the oath is a pain in the ass when in ranked (happened to me) and I wdonn't think I'll play Kalista in ranked ever again unless it's with a friend. And about Kalista being oathless, that's baasically goinng against everything she is made to do, her near entire kit is based on an oathsworn.