1 Nephi 12:16. Depths of Hell
Revelation 2:24 (“the depths of Satan”) is the source for the words “the depths of hell” in 1 Nephi 12:16. The book of Revelation, being in the New Testament, was unavailable to the Nephites, who left Jerusalem six centuries before Christ’s birth.
The words “depths of hell” are found in Proverbs 9:18. It is much more likely that, if the Book of Mormon is copying biblical idioms, it took this one from the Old Testament book—which, of course, may have been available to the Nephites. By the same token, one could argue that John borrowed the same Old Testament expression for the book of Revelation.