A Hell Hound

The thing is a hell hound, its fur is bluish flames, its eyes are pools of madness, and acid that leaves smoking holes in the carpet drips from its steel fanged jaws.

"Holy Shit!" You shout and scramble backwards.

The beast make's a running start ready to rip someone open...

Beverly doesn't even blink, just whips out a pistol you didn't know she had, a real one, and plugs the beast between the eyes.

The thing looks like it is going to shrug off having its brain pan scrambled then suddenly it shrieks in pain and starts clawing at its forehead with its knife like razor tipped claws and collapses on the floor, the flames winking out and it's blood eating through the wooden panels under the rug.

"What: in-the-name-of-God-and-all-His-Angels: was: THAT?" Jane says in horror.

"A Servant of the Arch Nemesis." Beverly states in a voice slightly higher than you expected, her normal Alto now a Mezzo-Soprano, though that could just be stress.