Related Clues:

• It's usually a bad sign
• It can be a good sign
• Substance banned in some schools
• Foreboding thing
• A sign of things to come, say some
• A comet was often considered a bad one
• The writing on the wall even for Norm Keane
• Gathering clouds, maybe
• Rainbow or ray of sunshine, perhaps
• Spilling salt is a bad one
• Scourge of sidewalks
• The Grim, in the Harry Potter books
• One might be good or evil
• A rainbow is said to be a good one
• Sign that might be described as 'ill'