When Klaus broke through to the Great Sage stage, the two lightning elements awakened alongside the second Flame element.
This was also why he could use the Lightning Source Diagram as his ultimate weapon during the battle in Union City. The Golden Annihilation Lightning was the lightning he used back then.
It is one of the most dangerous types of lightning out there. It crackles with a golden hue.
It has a burning effect; clearly, it could even harm sovereigns and above.
This was displayed during the battle in Union City. Klaus could tell that, aside from the burning effect, it also has stunning and, to some extent, torturous effects from even the smallest contact with it.
But that was the Golden Annihilation Lightning.
The Soul Yin-Yang Lightning was meant for soul attacks and physical attacks, with emphasis placed on the soul. It deals more damage to the soul than even some of the most powerful soul-attacking techniques out there.