The Dungeon Levels are the floors, stages or, well, levels of the Warrens. There's at least 8 of them, with all but one being associated with either Oric or one of his Siblings. Every one of them has a distinct aesthetic and flavor, as well as possibly a gimmick unique to that level.
The top level is where Ciro starts off at the beginning of his adventure, as well as where he meets Riltia for the first time. Being, effectively, the tutorial level, there is no boss, and the enemies are weak. It's thought that DL1 is either the floor with no sibling, Ciro's floor, or Riltia's floor.
Having been designed in the early days of TWoOtA, DL1 is relatively simplistic, being made of mostly square, small, white rooms with a top-down view.
Belonging to Proxxy, this level has mostly mechanical or electric enemies. Ciro and Riltia arrive here for the first time by descending a ladder from DL1, before being disposed of by a chute.
DL2's floor and walls are light brown, and covered in engravings that make them look like electric circuits.
DL3 is Cain's prison. A dark and sinister dungeon, it has a semi-constant anti-magic effect, that makes casting magic that requires rolls nearly futile. It houses the Dark Cathedral, and Oric has set up shop here. There's also an underwater tunnel, as well as a door that leads to an unknown location.
This level is covered in tiles of various shades of purple, and there's numerous pits leading into the Void.
This level is reminiscent of Metroidvania-style platforming games, and is brighter than the other levels (especially when compared to the one right above it). Everything's made of some beige material, and there's blooming cherry trees decorating the area. The sky appears to be visible in the background.
It is said that the Underside was meant to be a pseudo-DL, and Cherish's Soul Star was used to power it. It is unknown what effect removing the Star has on the place.
The Void is the space between the DLs, and plays a role similar to placeholder rooms (such as the Chris Houlihan room) in video games. Ciro and Riltia encounter Betweenford when they accidentally enter it the first time by placing a ladder in a DL1 room which didn't have a DL2 room right below it.
- I.e. Bullet Hell