It's actually kinda hard to say who will win. An invisible killer who no one will see until it is too late, or the vampire with over a million people's blood power to help him.

the police girl(if not in a blood rage) will probably die

It was the nazis, wasn't it?

And i whole-heartily agree with you since every time i picture slenderman, i picture this guy

I think Nergal was used as a partial base for Slender