vampire
A muron is, in the narration's phrasing, theoretically a vampire — a turning that did not go correctly. That makes them a product of the regime's own process rather than a folklore creature living alongside it, which is the reason they turn up where vampires have been at work.
As human Coen
The walkthrough fights one as human Coen in daylight, so a muron is not a night-only encounter. The scream is a range effect rather than a directional attack, which is the one thing directional defence does not answer.
As a vampire
No verified strategy is recorded yet.
Named on camera by Rebel Wolves, but heard through auto-generated captions. The spelling here follows independent community documentation of the creature, which describes the same failed-turning origin and the same stunning scream. Behaviour is from one pre-beta encounter.