Video from Bible Nerds
"Dr. Michael Heiser discusses what Eusebius might have meant when he mentions the Nephilim Spirits, Watchers, and "spiritual hosts of wickedness". from video introduction.
"The passage about which inquiry is made is Ephesians 6:12 – “For we wrestle not against flesh and blood, but against principalities, against powers, against the rulers of the darkness of this world, against spiritual wickedness in high places” (KJV).
In this context Paul begins his discussion of the armor of God by encouraging the saints to be strong in the Lord and in the power of his might (v. 10). In that strength and power, Paul admonishes the brethren to put on the whole armor of God that they may be able to stand against the wiles of the Devil (v. 11). In verse 12, Paul discusses the nature of the enemy against whom Christians struggle and why they need the whole armor of God to be successful.
This is the only passage in Paul’s writings in which he explicitly speaks of Christians’ struggling against evil spirit powers. Its uniqueness has led some to say that the passage is an interpolation; however, there is no manuscript evidence for its omission. In fact, while not as explicit Paul lays the groundwork for this explicit statement in Eph. 1:20-23 where he tell us that Christ, at the right hand of God, is “far above all principality, and power, and might, and dominion, and every name that is named, not only in this world, but also in that which is to come.” The scope of the victory wrought in the resurrection and exaltation of Christ is made clear in the listing of these defeated cosmic powers. Colossians 1:16 and 2:10, 15 are related passages. Certainly, there has been much discussion over whether these powers are good, benign, or hostile. While it may be that an absolute answer is difficult, beyond doubt these powers (“all rule and all authority and power”) are among the enemies that Christ shall have put down at his coming. Eph. 6:12 makes certain that the powers mentioned there are evil. Eph. 2:2 does the same..." from the article: Who are the spiritual host of wickedness in heavenly places?