Can you add a setting for the spectator camera to control whether people can view invisible players (You could probably test for a couple methods of making players invisible). Possible options could be "Always," "Teammate-only," and "Never." Only thing that might be worrying is if someone turns invisible when players are already spectating them. Still, it's one of the problems we've had with boss battles. It's nice to be able to spectate the boss, but not when people are constantly giving away his location if he's a class that can cloak.