Lives depend on us, all of us. It isn't enough to race around the country shouting orders or following commands. Times will come when you need to rely on your fellow hunters or share information without a word. Tied up and gagged, hurt or injured and unable to speak, blasted by some freakin' witches' curse, you have to communicate in some way.
This works for Sam and me, cause we've been together all our lives. I can read his facial expressions like a book, same as he can me. A raise in his eyebrow and I know someone else is in the room, invisible or not. Excessive blinking tells me he's not sure what it is and it may be something we've never encountered before. Waving hands, subtle flashes of fingers (sign language), even pantomime (think charades only without lots of movement), these are just the tip of the field, and you have to get across your information as well as receive it. Work out your signals ahead of time, have a plan. And a backup. You may be the one who's hurt, but you know where the survivors are, the way out cause that's the way you were drug in. Nothing can stop getting your message across.