In his devotional for Nov. 24, Ed Mathews writes on spiritual warfare. He mentions prayer:

Our strategy. In the end, prayer is the best weapon, Ephesians 6:18a. A saint on his knees makes the devil nervous. And, when prayer is uttered “in the spirit,” satan meets his match, Romans 8:26,27. Therefore, we “should always pray and not give up,” Luke 18:1. It is possible for believers, with one prayerful request, to marshal the mighty battalions of eternity, Matthew 26:53. We have a defeat-proof plan for a sure-fire-victory.