Set the mirrors up and just start namin the beings off- Bloody Mary, Beetlejuice, Candyman, etc.
Do it enough times- which may require some decent survival skills- and others not even connected to such legends may even shoe up just to see what the hell is going on.
Freddy Kruger: Wow, woud ya look at that? This is more fun than anything I’ve come up with in years!
Pinhead: It is...impressive.
FK: Better than your stupid boxes, for DAMN sure!
P: No it....sigh...yes, you’re probably right,
Guys from Cabin In The Woods betting board: “Who had infinite recursive summonings?”