Chapter 49The Tenth Plague, the slaying of the firstborn, being destructive of life, is attributed here to Mastema, not God:
For on this night—the beginning of the festival and the beginning of the joy—ye were eating the passover in Egypt, when all the powers of Mastema had been let loose to slay all the first-born in the land of Egypt, from the first-born of Pharaoh to the first-born of the captive maid-servant in the mill, and to the cattle.
Mastema had been helping the Egyptians in the previous chapter; the implication, presumably, is that Mastema is not against the Israelites but against humanity wherever he is allowed by God to be. Though actually in the previous chapter the Tenth Plague is attributed, along with the others, to God; this is either a continuity error, or an implication that God does not want to sully God's own hands, or those of the Angel of the Presence, with the dirty work, and outsources it to Mastema.
Like the author of Deuteronomy, that of Jubilees can't withstand the temptation to back-project the doctrine of the centrality of worship (in the author's own time at Jerusalem) into an earlier age:
When the children of Israel come into the land which they are to possess, into the land of Canaan, and set up the tabernacle of the Lord in the midst of the land in one of their tribes until the sanctuary of the Lord has been built in the land, let them come and celebrate the passover in the midst of the tabernacle of the Lord.