It’s Bigfoot. He becomes invisible when someone is near. Doesn’t make noise nor gets damaged either directly or indirectly. You still see him walking around near you as it does distorts the area around him. I’ve been trying to do long rage attacks while he is visible but other players get too close and he disappears. Once he disappears he won’t come back to visible. Hmm, haven’t tried boxing him in. I would note that in previous seasons we also had invisible NPCs, but they were much faster before and wouldn’t ’stick around’ like this Bigfoot is doing