When an action is so reckless that it will bring about one's own destruction, it is often too late by the time one realizes it. For Zasalamel, the appearance of Night Terror was the perfect example of this. Even he had underestimated the power of the cursed sword. It had far surpassed his own secret arts. During the ritual when Zasalamel tried to take the power of the sword for himself, it fused with not only the summoned Nightmare, but even the power of Soul Calibur, becoming a terrible incarnation of pure destructive will. It is likely that Zasalamel never even saw its form--Night Terror. Perhaps it had retraced the memories of the blue armour, or perhaps it had a remnant of the self-will that had formed while it used Siegfried as a host. Whatever the case, this entity bore a slight resemblance to Nightmare. It easily escaped Zasalamel’s control and appeared behind him, wielding it's power like a raging current, and obliterated him.
The man who had craved death met his end, though not in the way he had intended. In his place an unprecedented catastrophe gained wing and claw and was released upon the world.