Ghostly Flames are a hazard primarily found in the Lich Yard in Specter of Torment and King of Cards. They deal damage to the protagonist and knock him back on contact. There are two types of Ghostly Flames: blue and green.
Blue Ghostly Flames are the more common variety. When attacked, they will temporarily be reduced to a pile of ash which can be walked on safely,
Green Ghostly Flames can only be created by Nightmare Reize. When attacked, they disappear entirely instead of turning to ash.