The careful counsel that the king of Syria had taken in secret with his officers had been revealed to Elisha, who in turn took that information to Israel’s king.
Are come down.
Rather, “are coming down,” or, “are planning to come down.” What was revealed by Elisha was information concerning the plans that the Syrians had in mind, so that, having learned of those tactical plans in advance, the king of Israel was able to send sufficient troops to the places involved to cope with the Syrians at the time of their arrival.