Judges 9:56–57 tell us that God was still in control of all of this. God was the one who repaid Abimelech for his evil, the evil that he had committed against his father by killing his seventy sons. And God was the one who also made all the evil of the men of Shechem return on their heads. The Lord himself is the sole deliverer in this story.
56 Thus God returned the evil of Abimelech, which he committed against his father in killing his seventy brothers.