Kayn's Wall Indicator is Innacurate
Going out of the map causes his indicator to stay still and then eventually disappear or snap to a long distance away. Even if he's right next to you, the indicator doesn't always match up. This allows him to escape out of boundaries and you have no indication of which way he went, as well as him going out of bounds and coming up directly next to you without any indication he is there.
The indicator also fails on normal walls, because it doesn't update enough. The indicator will stay on the side he initially entered the wall, and not ever appear on the other side of the wall, and then Kayn will just appear out of the blue.
How to reproduce: Oh I don't know. How about actually play testing the champ.
I'd also suggest making the indicator visible, period. A dark patch on the ground can't even be seen over the bush transparency, and just looks like fog most on the small chance you do actually get to see it. Just make his model bright red inside the wall or something, and let us actually see his model exiting the wall, not just appear. If your vision engine can't handle that much, then you probably shouldn't have released a champ that is broken because of a bad engine.