The following video is a teaching session by street-healing evangelist Tom Fischer on evil spirits. He speaks about the fallen sons of man that Moses discussed in Genesis chapter 6, as well as historical information on the Nephilim as delivered in the book of Enoch. Though Enoch is not considered Canon by most Christians (the Ethiopian Orthodox Church does include Enoch in their Bibles) the book of Jude refers to its authority.
Tomn Fischer discusses fallen spirits origins and how evil spirits may use a variety of methods to attack Christians. He offers a prayer of deliverance for those affected by evil spirits and also discusses the principles of sowing and reaping.
Evil spirits aren't to be feared, as God has given authority to His children to defeat them through His name. Still, there is a responsibility that all believers have to walk in love, rebuke the devil and resist temptation, and to ensure they are keeping a humble attitude of brokenness and forgiveness and resisting anger, in order to keep evil spirits at bay.
Click the videos below to hear Tom Fischer teach on the subject as well as two videos that provide audio readings of the book of Enoch, and teaching by Steve Quayle on Nephilim giants.
Read the book of Enoch online
Watcher (Angel) Wikipedia article (use your best judgment when reading Wikipedia content)
Site that discusses photos of giants and a Cornell University hoax
The following video is highly controversial and many believe the photos captured are nothing more than a hoax. The video is included so you may watch and decide for yourself what you believe.
Steve Quayle: The Truth about Nephilim Giants (full video)