Judg 3:28, Gen 3:15, 1 Jn 3:8, Col 2:13-15
In the Old Testament, the judge Ehud killed the king of the enemy who was tormenting the people of Israel. (Judges 3:20-21, Judges 3:28)
Judges 3:20 And Ehud came unto him; and he was sitting in a summer parlour, which he had for himself alone. And Ehud said, I have a message from God unto thee. And he arose out of his seat. 21 And Ehud put forth his left hand, and took the dagger from his right thigh, and thrust it into his belly:
Judges 3:28 And he said unto them, Follow after me: for the Lord hath delivered your enemies the Moabites into your hand. And they went down after him, and took the fords of Jordan toward Moab, and suffered not a man to pass over.
The Old Testament prophesied that the coming Christ would break the head of Satan. (Genesis 3:15)
Genesis 3:15 And I will put enmity between thee and the woman, and between thy seed and her seed; it shall bruise thy head, and thou shalt bruise his heel.
Jesus is the Christ who broke the head of Satan according to the prophecies of the Old Testament. (1 John 3:8)
1 John 3:8 He that committeth sin is of the devil; for the devil sinneth from the beginning. For this purpose the Son of God was manifested, that he might destroy the works of the devil.
By dying on the cross, Jesus forgave all our sins and overcame Satan. (Col 2:13-15)
Col 2:13 And you, being dead in your sins and the uncircumcision of your flesh, hath he quickened together with him, having forgiven you all trespasses; 14 Blotting out the handwriting of ordinances that was against us, which was contrary to us, and took it out of the way, nailing it to his cross; 15 And having spoiled principalities and powers, he made a shew of them openly, triumphing over them in it.