Yeah, let's prolong it. I'm eagerly awaiting further guesses.
But now seeing your explanation, it is not that far. Only I would be reluctant in the "spell" part, because the spell certainly is not upon "me" (Moria) but just on the door. Which, in this scale you present (with "your friend lost" and all), is of almost no importance.
But you are really a skilled riddler, I favour you this.