Fallen Angels, Watchers, Giants, Nephilim and Evil
This easy-to-read book has full scholarly notes. Watchers, a class of angel, taught skills to humans and some slept with human women, the resultant progeny being Nephilim. For this they were thrown into Tartarus. Greek mythology speaks of "gigantes" (the Greek word for Nephilim) being thrown into Tartarus. Idioms such as the mistranslation "sons of God," are explained fully.