Dungeon Brick Walls are the background 墙s found naturally-placed in 地牢s. There are 9 different varieties, chosen at random during world generation. A single Dungeon may contain several different types in different areas. The Faction Flags present in a given Dungeon area will correspond to the Dungeon Brick Wall variant found there.
Dungeon Brick Walls cannot be crafted, but can be freed and collected with a 锤 or 雷管 after Skeletron has been defeated. Like naturally-placed 土墙s, Dungeon Brick Walls can only be mined from one of their edges (meaning that the wall tiles to be mined must be adjacent to empty tiles). As with all 墙s, Dungeon Brick Walls collected and placed by players will prevent 敌怪 spawns and can be used for valid NPC 房屋.
The type of Dungeon Brick Wall present in an area of the Dungeon, as well as the Faction Flags found there, will indicate which types of 困难模式 Dungeon enemies are most likely to spawn there after defeating 世纪之花. Enemies matching the wall type have a ~90% chance to spawn, while other enemies have ~5% chance. Faction Flags collected and placed by players will impact these spawns.