They come in 9 variants - brick, slab, and tiled, each in blue, green, and pink. They have the same ID as naturally occurring Dungeon Brick Walls when placed, and thus allow NPC spawns even when placed by the player. One can use them to create a functioning Dungeon anywhere in the world, as long as the other requirements (e.g. having 250 Dungeon Bricks onscreen) are met.
- Upon placing, destroying, and picking the walls up again the player will not receive unsafe walls and will instead get their normal variant, which when placed again will not count as a dungeon biome and will prevent NPC spawns.
- Enemies of a certain wall type (Tiled Walls for Diabolists, Slab Walls for Skeleton Snipers, etc) will only spawn if that wall type is placed behind the block that they would spawn on as well. By default, Brick Wall enemies will spawn in front of all Dungeon walls regardless of type, if that same type is not also behind the floor's blocks.
- These walls allow the player to build a sufficient arena in which the Ceaseless Void doesn't enrage.