The Marauder's Map

A magical map that revealed the plan for Hogwarts School and tracked its human and ghostly inhabitants and their movements, using the the Homonculous Charm. The map was not fooled by Invisibility Cloaks, Polyjuice Potions or Animagi. Created by the four Marauders; Remus Lupin, Sirius Black, Peter Pettigrew and James Potter whilst they were students at the school, the map referred to their aliases as Moony, Padfoot, Wormtail and Prongs and enabled the boys to traverse the castle and grounds in secrecy. The map could be revealed with a wand tap and the words 'I solemnly swear that I am up to no good' and hidden with a tap of the wand and the words 'Mischief managed.'