User blog comment:Trainsparency/2019 Spook and Sinister Hunting Thread/@comment-40266403-20191001210317/@comment-39764995-20191001232918

They are rare and take 3 hours, so unless you AFK in a private server for 5 or more hours you might not even find anything, in private servers you would have to ask for at least 5-10 hours to get one.