Cone of Caution

You create an illusion of a brightly colored knee- or hip-high cone or barricade. The cone or barricade can show a simple warning like "WET FLOOR" or "BRIDGE CLOSED". You can create a number of cones equal to twice your Profiency Bonus by casting this spell more than once. 

If a creature takes a Study action to examine the cone, the creature can determine that it is an illusion with a successful Intelligence (Investigation) check against your spell save DC. If a creature discerns the illusion for what it is, the illusion becomes faint to the creature.