Overlay Chart

Near-transparent skin kept rolled in a scarred tin tube, blank, and faintly greasy to the touch.

Laid over one existing map, plan, or elevation of a real place and left ten minutes, the sheet draws in what the original leaves out: sealed rooms, false walls, filled stairs, blocked drains, and every alteration made since the original was drawn. Lifting the sheet away clears it for the next map. It corrects nothing it is not laid upon, and shows no contents and no creatures.