Upon seeing the witches' circle, Robin says "I once went to an Ayahuasca ceremony in Iquitos." Ayahuasca is an Amazon shamanistic mind altering brew used in religious/spiritual ceremonies. Iquitos is a city in northern Peru that has built a small tourist industry around providing supposedly authentic ayahuasca drug trips/spiritual experiences to folks who believe tripping balls is, rather literally, divine.
First episode in this season that Granny appears