Logically speaking, the DLC final boss, if it's the evil Carmilla kept in check, is a hell of a lot weaker than the final boss of the main game. I doubt the gameplay representation for this will reflect this fact, but really this guy should be a stroll through the park in comparison. Literally, not even on the radar in the long run. In addition, Laura is hella weak for needing Gabe to take it down, despite how much they tried to build her up in the story of the main game.