because of thine iniquities thou shalt be accursed forever and it shall be [done 1ABCDEFGHIJKLMOPQRST|so N] and if the Lord shall say :
because of thine iniquities thou shalt be cut off from my presence and he will cause that it shall be [so 1ABCDEFGHIJKLMOPQRST|done N]
In these two verses, the 1906 LDS large-print edition switched the phrases “it shall be done” and “it shall be so”. This switch was undoubtedly an accident. The copytext for the 1906 edition was the 1879 LDS edition; and since its verses were set as paragraphs (even as they are today), it was easy enough for the 1906 typesetter to mix up the end of these two verses, especially since some of the phrases in both verses are identical:
Since the 1906 edition never served as a copytext, this error was never transmitted into any subsequent LDS edition.
Nonetheless, one may wonder here if the instance of “it shall be so” in verse 21 (the earliest reading) is an error for “it shall be done”, especially since elsewhere in this sequence of main clauses, there are no instances with so, only with done (including the immediately preceding one in verse 20):
Yet it should be pointed out that the instance in verse 21 is not quite the same since in this case (but not in the preceding cases) we have a causative expression:
Since the use of so in verse 21 is perfectly acceptable in English, the critical text will retain it, despite its unique occurrence in this passage.
Summary: Maintain in Helaman 12:21 the reading of the earliest textual source: “and he will cause that it shall be so”; the use of so here is probably not an error for done.