The Veil

The Veil appears to be the plane of existence that ghosts, hellhounds and reapersare able to inhabit. Phantoms that are inhabiting vessels are able to pierce through and perceive the Veil, as well as interact with spirits and reapers. Symbols such Enochian runes/warding can be painted and hidden within the Veil, and can only be visible to those who can pierce/inhabit it. A human will begin to see through the Veil once a crossroads demon contract is up, allowing them to see hellhounds and the true faces of demons. Piercing the Veil can be incredibly taxing for a spirit, and takes a lot of concentration. Spirits that try to communicate can get things jumbled, only being able to get through anagrams or word fragments.