Complex sentence: In the third book, "City of Glass", Valentine summons the angel Raziel, who accuses Valentine of the sin of pride, Lucifer's sin, just as his family name derives from Morning Star.
Split into simpler sentences: In the third book, City of Glass, Valentine summons the angel Raziel. Raziel accuses Valentine of the sin of pride, Lucifer's sin, just as his family name derives from Morning Star.