It was the Deep-sea Black Hole Torpedo.
That was what Watson had used the deep-sea submarine beneath him to launch. Its power was comparable to a full-force attack from a peak platinum-tier elite. Other than the Deep-sea Black Hole Torpedo, the deep-sea submarine Watson had developed also possessed two types of weapons. They were the Deep-sea Thunder Cannon and the Ultra-high Temperature Scorching Ray.
The deep-sea submarine was different from the one Watson had developed for the Ptolemy family. He had reorganized the third era's technology from the human race chess piece. By combining the void ships that the third era had built with divine technology and the gold-tier submarine, he had created that special submarine.
[A platinum-tier Deep-sea Behemoth Submarine.]
[This submarine was made from the remains of an ancient mythical creature. It had a mythical creature's activity and possessed the firepower of a magical weapon.[