Right after talking about the black dots and the "Fangs of Darkness", it is said that both are the manipulation of the void, literally saying that the black dots and claws are the void itself that is being summoned from hell ("It was the forbidden dark magic art, the manipulation of the forbidden void"), basically making it clear that the Fangs of Darkness and the black dots are the void being manipulated, and not the darkness, in addition to being said "The void unleashed", clearly being the void of hell, and the void is "being unleashed" from somewhere (hell), and he says that "The void unleashed in this world would not disappear until its negative energy was brought to zero", literally directly saying that the ability/darkness is the void, not the element of darkness.