Tonguez
A suffusion of yellow
.
I thought it was pretty obvious that Jack was a monster since the others were all described as having various numbers of “kills” whereas his were described as “deaths”.
When he first came down the Hallway with the markings on his face he reminded me of Boris Karloff so my first thought was “is there a Mummy in this too?”
But then he was named Jack which cleared that up...