Helaman 1:16

therefore the king of the Lamanites, whose name was Tubaloth, who was the son of Ammoron. Now Tubaloth supposing that Coriantumr, he being a mighty man, could stand against the Nephites, insomuch with his strength, and also with his great wisdom, that by sending him forth, he should gain power over the Nephites;

The king of the Lamanites was named Tubaloth. He was Ammoron’s son. Tubaloth thought Coriantumr was a mighty man. He thought Coriantumr could beat the Nephites with his strength and wisdom. By sending him, he would gain power over the Nephites.

Tubaloth was the Lamanite king at this time—Ammoron’s son. He figured that Coriantumr, being such a strong and brilliant warrior, could defeat the Nephites and help him take control.