The Concentration Cube is a harvestable that can be found in the Nightmare. It can be found from various sources and locations throughout the Nightmare including but not limited to:
- Being harvested from End of the Road, Fish Hall, Inside, Maze of Roots, Meeting Place, The Back Area, The Grand Hall, The Mansion, The Old Cave, The Old Mansion, The Road, The Supermarket, and The Theatre.
- A guaranteed drop from Democan.
In appearance, the Concentration Cube is a gray cube with indigo and black hues being seen towards the center of each side. If the player has no purpose for the Concentration Cube, it can be sold for 9,000 gold.