I was playing Kaisa (in her Valkyrie skin) and I noticed something weird, a visual effect that kept playing at seemingly random times
it looks like a bunch of ripples on the edge of your screen.
after a while i realized, it plays when someone off-screen uses hard CC to proc Kaisa's passive,
and im pretty sure its a reference to Xcom because it looks just like the 'aliens in FoW' effect that shows you the enemy direction.
I had no idea there was a visual indicator for when an ally applied passive to an enemy but I think it's really cool that it exists and just wanted to point it lol