Bare your soul

Before Arthur could dwell on the fact that he might be about to kill his servant, a voice boomed across the courtyard, the words cutting through him with an icy chill. He knew that voice, but never before had he heard it used with such venom. (Set in s02e01. It's up to Arthur to put an end to Sigan's destruction, even if the sorcerer's soul is currently trapped inside Merlin.)