perhaps it depends on the demon you're attempting to call
since I don't excel at fiddle playing I wouldn't likely think I'm going to end up on the plus side of that equation.
The dead hooker that you have in the trunk of your car...
Vampires---burial in the center of the "cross" of the crossroads is supposed to keep them in their graves.
I think the crossroads is also where Robert Johnson is supposed to have sold his soul to the Devil in return for being the greatest blues guitarist in the world. Hence the blues standard, "Crossroads".
I'll check with Marie Laveau just to be sure and get back to you.