Goblet of Fire

The Goblet of Fire is a goblet made of wood which sprouts fire at the beginning of every Triwizard Tournament used to choose the participating school champions, serving as an "impartial judge". The fake Alastor Moody (Barty Crouch Jr) says that the goblet is a very powerful magical object and it is very difficult to be hoodwinked, unless someone uses an exceptionally strong Confundus Charm.
During Harry Potter and the Goblet of Fire, it is placed in the entrance hall and surrounded by an "age line" (charm placed by Dumbledore). An age potion cannot fool the Goblet (it is proved by Fred and George Weasley).