Does anyone know the title of a film when these friend go to a house on halloween and turn into their costumes there was a girl with a snake arm and another girl that turn in to a cat women killer and the other friends turned too. Please help I've been seaching for this movie for years.

Halloweentown II: Kalabar's Revenge (2001) (TV)
I'm not sure if this is what your looking for,but it kind of fits your discription.

I said it KIND OF FITS. Just trying to help. Also, in your description where does it say anything about murders?

Is is goose bumbs kind of fits but idont think so