Despite all of the findings and adventure that he had, Nagan still couldn't shed his worry about the appearance of {Primal Wrath} outside of his kingdom.
With how there was no sign of it after he absorbed both of the gargoyles, an eerie implication was surfaced on his mind about how those guardians might not be part of the initial defenses of this planet, but that of a highly advanced civilization of {Primal Wrath} users who founded this place before him and claimed it by placing those gargoyles on the only entrance.
Or it might be just some mysterious entity's inheritance that was filled with all kinds of supernatural phenomenon and power of origins, which just coincidentally included the {Primal Wrath} to be one of the aspects of defenses that it possessed.