"My apologies, good man, entirely my fault that I got distracted so much." Ashnar says as he notices the farmer approach, and then listens to his plight.
"So we have a tower that comes and goes 'mysteriously,' crewed with what a farmer may consider 'spooks'. It is hard to formulate a good theory on that. I think we can rule out that the tower simply turns invisible. A curious farmer would find that out, and why would the 'spooks' only emerge when it is visible? The tower might be teleporting, or worse, plane shifting. Implying that there may be powerful magic at work. If it is plane shifting, it might go to the ethereal plane or the shadow plane, home to certain undead, which are commonly called spooks. But it is hard to tell what to expect."