Spectral Scum

You need to capture 5 of these creatures using a Scum Bag in order to enter the event room of the World Task "A Pirate's Death to Me". Some disappear after a successful journey in A Pirate's Death to Me.
Even when a Scum Bag is full, it can still be used to make remaining Spectral Scum disappear.

Attacks at a distance making their targets Drunk. They switch target often.

Use a Scum Bag in order to capture/kill them. Use invisibility to avoid getting targeted. They can be killed by anything stronger than it, by trapping them and having the stronger creature try to walk to it (e.g., by reaching a target). They no longer give any exp. Their corpse is the same as a Pirate Skeleton's and they yield no loot.