Oh, cool, the mist in the german version is yellow. For whatever reason... :shock:

I cast raise dead, to ask a question: are the mists still there?

Potentially Bosero went away (in real life he went to the army), never came back and his tower / lab is still protected during his looong absence by some active magic that causes the yellow mist to appear (and who knows what else may be hidden in the mist) and deter any uninvited guest (or raider...) from being too curious.