So, there are four ash spawn near the farm. I must have done some quests in the wrong order, because I decided to see what was at the farm and these four spawn attacked. No biggie... oh, wait. They are completely unkillable. Nothing I do does any damage to them what-so-ever. I tried dragging them back into Raven Rock and it was a complete massacre. I'm guessing they are unkillable because I finished the quest with Captain Veleth without visiting the site? Anyhow... MAJOR bug here, as they will completely destroy the game if they get into town (as I discovered).