• Iron Scent

  The rust monster can pinpoint, by scent, the location of ferrous metal within 30 feet of it.

• Rust Metal

  Any nonmagical weapon made of metal that hits the rust monster corrodes. After dealing damage, the weapon takes a permanent and cumulative -1 penalty to damage rolls. If its penalty drops to -5, the weapon is destroyed. Non magical ammunition made of metal that hits the rust monster is destroyed after dealing damage.