A. He causes bondage snares & oppression:

LUK 8:29. (For he had commanded the unclean spirit to come out of the man. For oftentimes it had caught him: and he was kept bound with chains and in fetters; and he brake the bands, and was driven of the devil into the wilderness.)

ACT 10:38. How God anointed Jesus of Nazareth with the Holy Ghost and with power: who went about doing good, and healing all that were oppressed of the devil; for God was with him.

ROM 8:15. For ye have not received the spirit of bondage again to fear; but ye have received the Spirit of adoption, whereby we cry, Abba, Father.

1TIM 3:7. Moreover he must have a good report of them which are without; lest he fall into reproach and the snare of the devil.

2TIM 2:26. And that they may recover themselves out of the snare of the devil, who are taken captive by him at his will.

B. Disease:

JOB 2:7. So went Satan forth from the presence of the LORD, and smote Job with sore boils from the sole of his foot unto his crown.

LUK 13:11. And, behold, there was a woman which had a spirit of infirmity eighteen years, and was bowed together, and could in no wise lift up herself.

LUK 13:12. And when Jesus saw her, he called her to him, and said unto her, Woman, thou art loosed from thine infirmity.

LUK 13:16. And ought not this woman, being a daughter of Abraham, whom Satan hath bound, lo, these eighteen years, be loosed from this bond on the sabbath day?

2COR 12:7. And lest I should be exalted above measure through the abundance of the revelations, there was given to me a thorn in the flesh, the messenger of Satan to buffet me, lest I should be exalted above measure.

C. And destruction:

JOH 8:44. Ye are of your father the devil, and the lusts of your father ye will do. He was a murderer from the beginning, and abode not in the truth, because there is no truth in him. When he speaketh a lie, he speaketh of his own: for he is a liar, and the father of it.

HEB 2:14. Forasmuch then as the children are partakers of flesh and blood, he also himself likewise took part of the same; that through death he might destroy him that had the power of death, that is, the devil;

1PE 5:8. Be sober, be vigilant; because your adversary the devil, as a roaring lion, walketh about, seeking whom he may devour:

1PE 5:9. Whom resist stedfast in the faith, knowing that the same afflictions are accomplished in your brethren that are in the world.

D. The devil does God's dirty work for Him:

1SA 16:14. But the Spirit of the LORD departed from Saul, and an evil spirit from the LORD troubled him.

1COR 5:5. To deliver such an one unto Satan for the destruction of the flesh, that the spirit may be saved in the day of the Lord Jesus.

1TIM 1:20. Of whom is Hymenaeus and Alexander; whom I have delivered unto Satan, that they may learn not to blaspheme.

E. Satan seeks to subvert the saints:

JOB 1:8. And the LORD said unto Satan, Hast thou considered my servant Job, that there is none like him in the earth, a perfect and an upright man, one that feareth God, and escheweth evil?

JOB 1:9. Then Satan answered the LORD, and said, Doth Job fear God for nought?

JOB 1:10. Hast not thou made an hedge about him, and about his house, and about all that he hath on every side? thou hast blessed the work of his hands, and his substance is increased in the land.

JOB 1:11. But put forth thine hand now, and touch all that he hath, and he will curse thee to thy face.

JOB 2:3. And the LORD said unto Satan, Hast thou considered my servant Job, that there is none like him in the earth, a perfect and an upright man, one that feareth God, and escheweth evil? and still he holdeth fast his integrity, although thou movedst me against him, to destroy him without cause.

JOB 2:4. And Satan answered the LORD, and said, Skin for skin, yea, all that a man hath will he give for his life.

JOB 2:5. But put forth thine hand now, and touch his bone and his flesh, and he will curse thee to thy face.