A long time ago, it started out as a harvest season tradition. Kids would dress up in costumes so that spirits wouldn't recognize them, since the end of fall is when weird shit tends to happen. Those kids would go around collecting food to appease those same spirits.

It fell out of practice seriously due to a few reasons, I think, one amongst them being that meisters like himself actually proved waaaaay more effective, and then it just became a fun holiday for dressing up and spooky stuff!

[He knows random facts like this, but fails all his practical classes back in the academy. This child...]