A Magic Lantern Show was an event in the childhood of Will and Alyss where skilled and specially trained performers would take a fire, put a special colored piece of film in front of it, and projected it on to the wall. They would then move it around and show several at once the given effect of dancing and to tell a story. It was a time of fun and entertainment for the children in the ward as Baron Arald paid for it out of his own pocket.
Years later, in Norgate Fief in book five, Will and Alyss discovered that they had been tricked, and the apparitions in Grimsdell wood were images projected onto the thick fog that inhabits the forest, just like a magic lantern show, created by Malcolm to keep people away from his home. This same technique was used by malcolm to create the face of Serthrek´nish in order to scare General MacHaddish into telling him about Keren's plans, and also to create the diversions used to cover Horace and Will's initial assault on Castle Macindaw in The Siege of Macindaw.