# You offspring of vipers, who
"You evil poisonous snakes! Who" or "You are evil like poisonous snakes! Who"
# who warned you to flee from the wrath that is coming?
John rebukes the Pharisees and Sadducees. Alternate translation: "you cannot flee from God's coming punishment like this." or "do not think that you can flee from God's wrath just because I baptize you."
# flee from the wrath that is coming
"run away from the punishment that is coming" or "escape because God is about to punish you"