Dungeon Maps are an item introduced in the Oberon update that can be obtained as a loot drop from mobs and dungeon chests. They allow a party to open a hidden entrance to a Randomized Dungeon of greater-than-normal difficulty and rewards. Maps exist in the range of Adept to Elder (T4 to T8) with the possibility of uncommon, rare and exceptional variants.
When used, a new dungeon location of the same tier as the map is activated on the world map, and the map user will see indicators of the shortest path to it on their mini-map. The entrance only spawns once the player who used the map reaches it, meaning it remains hidden from others up until that point. Once the location is discovered, however, the dungeon is fair game for all groups--the map's users will be the first to enter, but they might not be the last.