This prophecy is pretty straight forward.  While a multitude of judgments are unfolding on the AntiChrist and his kingdom, God will cause the Euphrates river, one of the most dominant natural forces that protects the middle east from eastern invasion, will dry up and go away, allowing the kings of the east (Likely China, India, etc) to move west into the middle east to do battle with the AntiChrist in an attempt to break free from his tyrannical rule.  So this event itself is not an actual judgment, but merely helps facilitate other events that are about to unfold at that time.