A dungeon is any enclosed, hostile area made up of interconnected encounters. It could be a cave system, a castle, an insect hive, or any other space that can be subdivided into different distinct areas where each different encounter takes place. Last Odyssey is not a game about dungeon crawling per se, but dungeons are a natural way to contain quests or even entire adventures. In particular, the Domains of Monsters will often be dungeons. There are no hard and fast rules for creating dungeons, but GMs should think of them as a series of rooms connected by doors. Each door has a specific requirement for passing through it, and each room either hosts an encounter or is an empty area for the party to rest. Most dungeons will be represented by a single node on the overworld, but extremely large ones will instead contain two or more, in which case GMs should treat the paths between them the same way they treat paths in the overworld, with encounters, a navigation difficulty, and a weather table if appropriate. In addition, many dungeons will also be divided into levels, which are distinct zones that represent different interconnected areas. In some cases, a level will be a literal level of a building, while in others levels might be adjacent systems of caves or mark the transition between different biomes. Whenever the players enter a new level of a dungeon, they earn 1 Discovery XP.
As the player characters progress through a dungeon, they will accrue injuries, status effects, and lose HP and MP. If they manage to make an area safe enough, they may rest. If players rest inside of a dungeon, they will play out a Camping Phase as though they were traveling. If there any enemies remaining on their current level that would theoretically be aware of the characters’ presence and able to invade their resting place, the danger rating of the dungeon counts as being equal to 10 for the purposes of determining if an ambush occurs. In the event that the player characters are ambushed, they should be ambushed by a group of enemies that already exists within the dungeon. Resting advances time as well, which will have other consequences. Smarter enemies will prepare ambushes for the player characters to walk into, traps will be reset, and wandering creatures will move from level to level.
To create a new dungeon in Last Odyssey, the GM should employ the following steps: