Bloodwax

Wondrous item, uncommon
  Take one enchanted bloodwax candle, add to it one drop of a target creature’s blood, and light. For the next 48 hours, or until the candle is extinguished, a ghastly red trail hangs in the air leading directly to the creature from whom the drop of blood was taken.
  Once the candle has burnt for 48 hours in total, it is depleted and cannot be used again. Each time the candle is lit and extinguished, a minimum of one hour’s worth of wax is consumed.
  This trail can’t pass through solids or liquids, and is undisturbed by wind of any strength. The candle cannot distinguish between identical twins or clones and will instead create a trail to each. If the creature is a construct, or the creature is on another plane, the pall of red smoke listlessly hangs in the air.