The Devil's Shoe Horn is a supernatural vortex primarily used to swallow up all non-demonic life. It first appeared in "Displaced Aggression Issue 4" of the Ghostbusters IDW Comics.
The Devil's Shoe Horn is a gateway that once the stones of Stonehenge are properly aligned, will banish every living being to the farthest depths of the Netherworld while simultaneously allowing every form of ghost, demon, and spirit to arise in their place.
Koza'Rai attempted to open one in Central Park. Rachel Unglighter and Peter Venkman used a rope, pulley, and lever still attached to a stone to knock the structure over. Somehow, this led to a reconfiguration with a reverse polarizing effect on the Devil's Shoe Horn. All demons and ghosts were pulled into the Netherworld, including Rachel.