Leading up to, and including, the wall of flesh domain you may have started dropping Explorable Maps. These explorable maps can be used in the Map Device to travel to new lands to continue your adventure.
Explorable Maps will have a theme and a tier associated with them. The theme of the map will determine the type of biome the explorable map is in and the tier of the map will determine the area level and the difficulty of the map.
Completing and exploring these maps is the core foundation of the endgame system.
Each map has a randomly generated layout that contains an “end” area that includes a boss. The boss is random based on previously defeated bosses as well as some path of terraria specific mini bosses or enhanced mobs.
Upon killing the boss the map is considered complete and you will get completion for the map. Map completion is used for a variety of things, such as the leaderboards, quest completion, and endgame progression.
Possible map themes includes