It appears during the second game of hide-and-seek with Oliver, forcing the party to Hide and into Turn-Based Mode. The party either has to sneak their way into the ruined house where Oliver will be appear in two turns or attempt to fight the powerful shadow which is backed up by Mummy and Doggy.
The wraith appears again during the final confrontation with Oliver at the heart of Reithwin Town, even if defeated earlier.
Beware: this attack has a hidden AoE: 5 m / 16 ft (Radius) effect. Even if it misses its target, nearby entities will also endure a separate Attack roll.
On a failed Constitution saving throw, total Hit Points are decreased. If lowered to 0, the creature ignores doing Death Saving Throws and will instantly die.