@Reneskie
It's actually found in a few manags, although the one I was thinking of the guildmaster notices that his lips don't match his words and due to his unusual power they get suspicious. He used a phrase that was previously recorded in their history which a different "otherworlder" used to say but the guildmaster himself didn't even know what the words he said actually ment.
I don't particularly remember the story name at the moment though.
