Theme Override Volumes let you apply another theme on certain portions of your dungeons that are covered by this volume. These are useful for adding variations to your dungeons.
Asset/DungeonArchitect/Prefabs and drag drop the
ThemeOverrideVolume prefab on to the scene
Move and scale it to cover a certain portion of the dungeon
Select the theme override volume you just dropped and inspect the properties and assign the DungeonGrid reference
Assign a theme you'd like to apply within these bounds. Then hit
Rebuild Dungeon button