In Call of Duty Advanced Warfare, sometimes I can see enemy players through walls as red shadows.
They come and go, sort of long blink type of "coming and going." The effect lasts for a while, I think it must be 10-15 seconds.
Obviously this is some kind of effect created by a player.
My question is what item/perk/whatever it is that creates this effect?
I thought it would be the Threat Grenade, but I have yet to figure out how that one works, I shoot it into the area, and it detonates but it doesn't seem to show me any threat indicators. Would it have to detonate and "infect" enemy players?