Soul That Completed the Count

The 70th (unlisted) soul completed the count and contributed to the Jews’ ability to cope with the darkness and to accomplish the purpose of exile (birur & bitul) in preparation to Matan Torah.

Based on Lekutei Sichos חלק כ' פרשת ויגש

Other options mentioned:
Asnas – wife of Yosef, already in Egypt, and possible daughter of Dena, daughter of Leah.
Serach – worthy to be mentioned twice since member of the group that entered Mitzraim and also the group that left Mitzraim.
“sons of Dan Chusim” – Dan had an additional unnamed son that did not have a child and thus was not listed.