In fact, I think the other two iterations of Miss Karlov like the new Kaya, as well: Teysa, Orzhov ScionTeysa, Orzhov Scion likes Kaya because the tokens she makes are white, giving her more sac fodder, while Teysa, Envoy of GhostsTeysa, Envoy of Ghosts is a million mana, so being able to bounce her back to your hand instead of the command zone is a huge weight off of command tax
Retether represents a level of powerful spell that Auras need a little more of
Even the best idea can fail if it isn't designed correctly
To determine the total cost of a spell, start with the mana cost or alternative cost (such as a miracle cost) you're paying, add any cost increases, then apply any cost reductions
If you can cast him in the same turn that he is removed, you'll get maximum return from his token spawning ability