The power of prayer comes from strengthened relationship with God and the cleansing and sensitivity to godliness it brings. It is neither biblical nor wise for ministers of deliverance to invite a demon into themselves in order to get it out of a demonized person. The rationale for this practice is that the trauma of exorcism will be eased because transferring a demon into another body is less difficult than casting it out into bodiless existence. Nowhere is there warrant in Scripture for willfully inviting demons to enter a person. Jesus' allowing the demons in the Gadarene demoniac to go into pigs in no way validates the practice of transferring demons into people.
Scripture is the only reliable source of information about demons.
The contemporary demonologies, including such matters as demonic hierarchies, motives and methods of demons, are largely composed from information gathered from the demons themselves. At best information from them will be tainted by untruth and evil motive or half truths in a misleading way. Believing demons' reports will often bring great harm to the cause of Christ. Therefore information gained from demons should not be used for any purpose. Under no circumstances should Christians carry on conversations or arguments with demons.