Will o' the wisp

A will o' the wisp was believed to be a glowing light that would lure people to their doom. The Seventh Doctor worried that will o' the wisps existed alongside the other myths of Tír na n-Óg. (PROSE: Cat's Cradle: Witch Mark) The Sentience's ectoplasmic manifestations were reminiscent of will o' the wisps. (PROSE: Nightshade)