I own one of the first Bad Stones and Electric Mistresses made.I have used them together for some very cool effects.I put the Bad Stone first and run it through the Electric Mistress.I set the Bad Stone on a medium fast setting at a medium depth,then I set the E.M. at a slow sweep and set the depth about halfway. The combined effect gives you a very addictive warble and just playing with the speeds and intensities can give you a myriad of the coolest modulating effects that you’ve heard.

BTW:Running 2 flangers or phase shifters together at different speeds and intensities also gives you some great modulating options.