John’s tour guide for the vision of Revelation 17 was “one of the seven angels who had the seven bowls” (Revelation 17:1). That angel had taken John from heaven (where he had been since Revelation 4:1) to “a wilderness” ( = this earth in its fallen condition, Revelation 17:3). So it was on earth that John had been told of the demise of the prostitute (Babylon) and her colleagues. That now “another angel” appears (the term “angel” means “messenger”) indicates that we need to pay attention to who now sent him (and why) and what his message is. That he “came down from heaven” is to say that God in heaven sent him with a message for John (“down”) on earth (see further Hebrews 1:14; Psalm 103:20). His message will give perspective to what the former angel had told John.