You trace a path on a solid surface within range in a straight line up to 60 feet long. The path is nearly invisible and requires a successful Intelligence (Investigation) check against your spell save DC to find.   Whenever a creature steps onto the path for the first time on a turn or starts its turn there, a 5-foot-wide circular blade of magical force protrudes from the surface and travels along the path before vanishing. Each creature within the path must make a Dexterity saving throw, taking 4d6 slashing damage on a failed save, or half as much damage on a successful one.