[Source] Moritz Diefenthel is a sorcerer and an old acquaintance of Triss Merigold's first encountered by Geralt during the masquerade ball at the Vegelbud Residance. Spoiler warning: Significant plot details follow.Later, sadly, due to his refusal to leave with the other mages to Kovir, he can be seen tied to a burning pyre outside the Glory Gate of Free City of Novigrad. Geralt has an option to rescue him by killing witch hunters nearby or do not interfere. Regardless of Geralt's choice, there won't be any consequences. Significant plot details end here.