10. Marauder’s Map
Fred and George Weasley have had Marauder’s Map for years and yet not once had they noticed on it that there’s always one more name next to their brother Ron almost wherever he went: Peter Pettigrew. Or when’s in Harry’s possession he didn’t notice that Mad Eye is in fact Barty Crouch Jr. And before you say “they are disguised”, we are talking about the magic item that was able to detect Harry Potter under his invisibility cloak, a cloak powerful enough to hide his wearer from Death itself.
