Ghosts are ethereal undead creatures.
Ghosts were undead that could pass through walls. They also had a specialization in hit and run tactics to touch you with their weakening touch and deal damage. Due to their intangibility, they were immune to physical attacks.
In YGGDRASIL, there are powerful exclusive, racial classes for ghosts which are kept hidden to be discovered. If ghosts have managed to acquire such classes, they can then develop stronger incorporeal traits as long as their racial levels increased. This even includes resistance to perfect visual effects, not needing liquids or food, and invalidating fatal hits.
- So far this monster is only mentioned in the Web Novel.