The Demon Descend.
It was the martial art Blackie had acquired in the Demonic Abyss.
At the time he got it, he didn't use it, not because he didn't want to, but because whenever he practiced this set of techniques, he felt unable to unleash their full power, always seeming to produce just a regular punch.
He even thought he hadn't grasped the basics yet, trying to practice it every time he tempered his body, but sadly, it still had no effect.
However, after all memories were restored, Blackie realized he had used this set of techniques in his past life, even though it seemed a bit different from the one he acquired in the Demonic Abyss.
It wasn't until he went to the Demon Realm and activated his bloodline that he finally discovered he could use the first move, Heaven Breaker, upon practicing The Demon Descend again.
These techniques of The Demon Descend could only be used after activating the Holy Demon Bloodline, enabling one to step through the threshold.
