Prophetic witchcraft is one of the biggest dangers of the prophetic ministry. It is dangerous to both the ministers and to the recipients, and it even threatens the church itself.
Witchcraft, from a biblical perspective, is about illicit power. Authorized power comes from submission to authority. We first submit to God as the ultimate authority, then we submit the the earthly authorities: governments and parents especially. It is from these submitted relationships that we should get the power we use. If we obtain or use power in contradiction to the submission of these relationships, then that power is a form of witchcraft. 1 Samuel 15:23 points out that rebellion (which is rejecting authority) and witchcraft are intimately linked.
Let's look at divination. Divination is obtaining information illicitly. It can be information about the future, about something happening somewhere else, or about people who are dead. This is information that a person seeks out for their own purposes. In contrast, the godly way of seeking information is to inquire of God. The difference is that God may say no, He may give only a part of the information requested, or He may tell you to wait. Part of the relationship with God is that He has the right to tell us no and we must trust that He is doing so in love. Divination, on the other hand, does not invite God's love into our lives, it only wants to get its own way. So if we are engaging in divination instead of prophecy, this is witchcraft. But prophetic witchcraft goes beyond divination.
The broader risk of prophetic witchcraft is control. Prophecy is a powerful ministry because people who truly believe in the prophetic words will operate in obedience to the prophetic words. This power creates temptation for a prophetic minister to use prophecy to steer people in a desired direction. This temptation may seem to the prophetic minister to be a desire to help, but it is actually control. When we use prophecy - either genuine prophetic words or false ones from the wrong spirit - to manipulate or control another person, this is also witchcraft. 2 Corinthians 3:17 tells us that where the Spirit of the Lord is, there is freedom. When we manipulate or control another person, that is taking away their freedom. So any prophetic ministry that is used to manipulate or control others is coming from a spirit other than the Holy Spirit.
Fortunately, the Bible has built-in safeguards against prophetic witchcraft. The first is for the prophetic minister: humble yourself and God will exalt you (James 4:10, Matthew 18:4, Matthew 23:12, Luke 14:11, Luke 18:14). Because witchcraft requires self-exaltation, humility is the primary prevention from falling into it. Second, the church has the safeguard of testing prophecy. 1 Thessalonians 5:20-21 and 1 Corinthians 14:29 clearly point out both the individual and the community burdens to test prophetic words. When we know that our prophetic words will be judged, we are less tempted to control people and the others around us are more ready to resist that control. Of course both of these measures can fail if a person is determined to participate with witchcraft, but when a community's prophetic culture expects humility and mutual accountability, then the risk is reduced.