I’m not exactly sure what type of creature it is. It’s not an apostle, yet it can create psuedoapostle-like beings and Gut’s brand bleeds to it’s presence. On top of that it can’t be a creature from the astral realm since it’s implied that it’s an ancient creature so it couldn’t have come from qlipoth or Griffith’s world merger. So what type of creature is it? The berserk wiki says that it gained it’s manifestation in the physical world after the world merger, but that makes no sense because the merrows have been fighting it for far longer.