[ "Demonic Emperor Sword: Cataclysmic Destruction" ]
Zero used Cataclysmic Destruction when he felt that Kurtis was having a hard time keeping up with him.
Cataclysmic Destruction used to be one of the strongest attacks that would really stress his body. However, thanks to Ancient Dragon's Heart, he could easily use it without experiencing any kind of side effect.
!!!
On the other side, Kurtis who was hatching some plan to distract Zero was surprised when Zero was using Cataclysmic Destruction. He could feel it deep inside his bones that Zero's next attack would be very terrifying.
Despite his mana depleting quickly, he decided to strengthen his mana barrier and then gathered Dark Energy to counter it. Not only that, he decided to use his final Trump card.
He took out a Devil Fruit from a storage ring and ate it. It was a Rank-A Devil Fruit that could increase his strength and mana. It was an extremely rare resource and even a Rank-S Devil coveted it.