Phantasmagoria

You may be looking for the audio story.

Charles Dickens refered to a Gelth-possessed corpse as phantasmagoria. (TV: The Unquiet Dead)

Emily Holroyd recalled that the Torchwood Institute was created to combat the threat posed by the Doctor and other phantasmagoria. Jack Harkness clarified that the Doctor was not a threat and was infact "the one who'll save you from your phantasmahoojits." (TV: Fragments)