It seems bad strategy for Moroni to insult Ammoron (“child of hell”) but simultaneously expect Ammoron to agree to a three-for-one demand. As I read this passage, Moroni is attempting to negotiate from the most powerful position. Because he claims that he is ready and willing to destroy Ammoron, Ammoron’s agreeing to a three-for-one trade would simply be Ammoron’s recognition that Moroni was in the stronger position and able to dictate terms.
Culture/Translation: “Child of hell” most likely emerges from Joseph’s vocabulary and religious world. The ancient Israelite concept of Sheol would not have had the same connotations that “hell” would develop for later Judeo-Christian religion. (See commentary accompanying 1 Nephi 15:28–29.) Probably the plate text indicated that Ammoron was a “child” of a specific pagan god, thereby denying (which he already had) that he was part of the father-child covenant that Nephites had with Yahweh (Mosiah 5:7). As the child of another god, Ammoron was foreign to Yahweh’s covenants and therefore denied heaven—hence, a “child of hell.”