Being an undead Horror, appearing quite suddenly in the Garamsythe Waterway to terrorize those who venture near. It is said Wraiths are the Coalescence of the lingering Regrets of those who perished in a tragic Accident during the Waterway's Construction. Many of those who died were Fathers, and their Thoughts for their Sons and Daughters cause this Creature to appear most often near Children. A Woman, worried for a frightened Child, posted a Bill for this Mark.
It is best to stock up on Antidotes and Potions before the battle to deal with its Poison attacks. Potions can be used to cure party members or to dealing damage to the Wraith, as the Wraith is undead and curative spells and items deplete its HP.
Immediately when Wraith shows itself, it will cast Doom at random - this can usually miss - until all party members are affected. When everyone is doomed, it will switch to physical attacks, which can inflict Poison or Sleep or even a touch of both. At HP Critical HP, Wraith will start using magic attacks like Dark and Blizzard.
The one strategic disadvantage of the Wraith is that once it is inflicted with Silence, it is basically harmless; it can only use Doom and physically attack. If one has got enough LP, getting the Remedy Lore which can cure Doom is of help. Otherwise, as long as everyone's countdowns won't expire at the same moment, Doom won't be too much of a problem if the player has Phoenix Downs. Because of the Doom it is best not to pursue the hunt with Vaan alone as soon as the hunt becomes available, but to wait for Basch and/or Balthier and Fran to join before trying it.
Defeating Wraith allows the player enter a private residence in Lowtown and pick up the Dusty Letter key item. This letter is part of a later sidequest and tells in which order the sluice gates must be operated in the waterway.