Complex sentence: At Criss's prompting, Poncia was brought in to produce two Kiss albums--1979's "Dynasty" and 1980s "Unmasked", he sung backup vocals and helped with songwriting on both albums.
Split into simpler sentences: At Criss's prompting, Poncia was brought in to produce two Kiss albums--1979's "Dynasty" and 1980s "Unmasked". He sang backup vocals and helped with songwriting on both albums.