As discussed under Alma 12:8, scribe 2 of π frequently omitted the conjunction and. Here in Alma 12:10, Oliver Cowdery supplied the and when he proofed π against π. Clearly, either reading (with or without the and ) is possible in this context; thus there would have been no reason for Oliver to add the and on his own. The critical text will follow the corrected reading in π.
Summary: Accept Oliver Cowderyβs addition in π of and at the beginning of Alma 12:10 (the probable reading of π, no longer extant here).