Lester Dickey, in an unpublished article “Engraving the Book of Mormon” (dated 22 April 2001, received by me in October 2003), suggests that the on here in this verse is intrusive and should be removed from the text. 𝓞 is not extant here; 𝓟 and all the printed editions have on—and without any textual variation. More significantly, the phrase “to lead someone on” occurs elsewhere in the Book of Mormon:
This phrase often implies deception (as in the two Alma citations). But the phrase “to lead someone on” can also simply mean ‘to lead someone’, as in the Jacob 4:15 example. We get the same semantically neutral usage in the King James Bible: “and he led them on safely” (Psalm 78:53).
Here in Helaman 6:28, the verb phrase “to lead on” actually has the sense of deception, but the punctuation makes it difficult for the reader to recognize that. The 1830 typesetter placed a semicolon after the first relative clause that postmodifies the noun phrase the people; this forces a more neutral sense for the verb phrase: “and it was that same being which led on the people which came from that tower into this land”. The problem here is that Satan did not lead the Jaredites to the promised land at all. Instead, the book of Ether expressly states in various passages that it was the Lord who led the Jaredites to the promised land, as in Ether 7:27: “and he remembered the great things that the Lord had done for his fathers in bringing them across the great deep into the promised land”. What we actually have here in Helaman 6:28 is a statement that Satan led on the Jaredites to spread the works of darkness and abomination, thus dragging them down to destruction:
The relative clause “which came from that tower into this land” is restrictive and definitional; its only purpose is to identify these people as the Jaredites (“the people which came from that tower into this land”). On the other hand, the subsequent relative clause (“which spread the works of darkness and abominations over all the face of the land”) directly relates to the preceding led on; that is, the last relative pronoun, which, refers either to Satan (“it was that same being ... which spread the works of darkness and abominations over all the face of the land”) or to the Jaredites themselves (“it was that same being which led on the people ... which spread the works of darkness and abominations over all the face of the land”). But clearly it is not Satan who led the people from the tower of Babel to the promised land.
Summary: Remove the semicolon from Helaman 6:28 so that the expression “it was that same being which led on the people”, with its sense of deception, correctly refers to Satan’s influence on the Jaredites in leading them on to works of darkness and ultimately causing their destruction; the relative clause “which came from that tower into this land” is restrictive and simply defines these people as the Jaredites.