A Dungeon is a set of rooms where players must defeat monsters in one room to progress to the next room leading to a final boss.
In many Dungeons, you can also fight unique monsters that drop special items, crafting ingredients and various loot. In higher level dungeons, after completion, a chest will appear containing a special Haven Bag decoration.
Some dungeons are unique to specific Nations while others have slightly different rewards based on which Nation they are present in. Dungeons that are present in all four nations are linked and party members can enter from different nations and end up in the same instance of the dungeon.
Most dungeons have dungeon machines, which you can get items from with dungeon tokens. Dungeon tokens can be obtained by defeating the boss of the dungeon. You can only use the dungeon machine if you have the token for the dungeon machine. Like, if you have a celestial piwi token, you can't obtain items from the tofu machine. Dungeon machines are usually present next to the dungeon. If you buy and item from the dungeon machine, you cannot merge set items with it. There is also a token called a basic token that is usually used in any machine.
In each dungeon are levels of stasis, if you have the stasis set to 11 the level will be normal. The levels of stasis are designed so that low-level players can fight in high-level dungeons. By increasing the stasis, you will get more rewards and xp, but the monsters will be tougher.