Complex sentence: Despite all the pain and destruction caused by the plagues, Rameses refuses to relent, and in anger, when Moses confronts him again, vows to finish the work his father started against the Hebrews, unwittingly providing the stipulations of the final plague.
Split into simpler sentences: Despite all the pain and destruction caused by the plagues, Rameses refuses to relent. In anger when Moses confronts him again, vows to finish the work his father started against the Hebrews, unwittingly providing the stipulations of the final plague.