Bible Question: Tell me about the Witch of Endor, "familiar spirits", mediums. 

It was Saul and you can find it in the book of 1 Samuel in the 28 chapter. 

[7] Then said Saul unto his servants, Seek me a woman that hath a familiar spirit, that I may go to her, and enquire of her. And his servants said to him, Behold, there is a woman that hath a familiar spirit at Endor.
[8] And Saul disguised himself, and put on other raiment, and he went, and two men with him, and they came to the woman by night: and he said, I pray thee, divine unto me by the familiar spirit, and bring me him up, whom I shall name unto thee.
[9] And the woman said unto him, Behold, thou knowest what Saul hath done, how he hath cut off those that have familiar spirits, and the wizards, out of the land: wherefore then layest thou a snare for my life, to cause me to die? 1 Samuel 28:7-9 

The following is a small lesson with a lot on content on the subject. It came from one of the very first multi-media productions in the world. The date was 1916. The production used a combination of hand painted slides, a record player and personal addresses. It was called "The Photo Drama of Creation." 

The Witch of Endor

We have already noted that the fallen angels at the
time of the Deluge were barred from further materialization.
Since then they have sought otherwise to influence humanity. Few would communicate with them if they knew their real character; hence they represent themselves
as being our dead friends and relatives. As such they
attempt to communicate with the living through "mediums,"
who are deceived, else they would not serve as "mediums" for demons.--Isaiah 8:19;Deuteronomy 18:9-12.
In olden times these mediums were called witches, wizards,
necromancers. They had "familiar spirits," or were familiar
with the spirits who were disobedient in the days of Noah.
God had forewarned Israel against these evil spirits and their mediums. He said that no such mediums should be permitted to live in the land of Israel. They might operate amongst nations not under Divine care, but God’s representative, Saul, was commanded to put to death all such. When King Saul got out of fellowship with God, who refused further communications, he turned for advice to a witch at Endor, and asked her to awaken Samuel the Prophet, who meantime had died. The evil spirits impersonated Samuel easily enough, and the witch gave the King messages in his name, whereas Samuel was dead and could not give or receive messages. King Saul saw nothing; he merely received an answer from the witch, who said she saw and heard Samuel. The evil spirits have some way of knowing much respecting the future. But anybody under the circumstances might have known the fate to expect for Saul and his army. The King himself knew what to expect. It was this that troubled him and led him to seek the witch, contrary to the Divine command. It is not for a moment supposable that God and Samuel, having
refused to communicate with the King, would change and permit a witch, condemned by the Divine Law, to overrule the matter.--1 Chronicles 10:13,14.

Bible Question: Fallen Angels Materializing Today?
In the pre-flood days, when the angels came down & had relations with the daughters of men, were the offspring (Nephilim) always sons? And what stops the fallen angels from doing this today?

THREE WORLDS. In order to understand the status of the fallen angels today, it would be good to go back to see what was happening in the “the world that then was, being overflowed with water, perished” (2 Peter 3:6). Apostle Peter tells us actually that there were three worlds—periods of time under a specific rulership. After the “world that was” is the “present evil world” under Satan, the “god of this world” (2 Corinthians 4:4). The “new heavens and a new earth, wherein dwelleth righteousness” under Christ’s reign is the third world.

FIRST WORLD RULED BY ANGELS. Although no specific scripture says so, Apostle Paul makes the statement, “For unto the angels hath he not put in subjection the world to come, whereof we speak” (Hebrews 2:5). From that statement, we may conclude that the angels were charge of the “first world” after man’s fall and up to the flood. They were given the opportunity to rule over mankind. Instead , the sons of God saw the daughters of men that they were fair; and they took them wives of all which they chose” (Gen 6:2). The results were disastrous because the resulting children, Nephalim, created more evil in the world than ever.

FALLEN ANGELS CAST INTO TARTAROO. These fallen angels did not stay in the spirit realm, but materialized and came to earth and made worse the downward fall of man by intermarrying and producing giants of despicable character. In the flood they returned to the spirit realm but were then confined to a certain place until a certain time—the Judgment Day. “And the angels which kept not their first estate, but left their own habitation, he hath reserved in everlasting chains under darkness unto the judgment of the great day” (Jude 6). Where are they kept until then? 2 Peter 2:4 says, “For if God spared not the angels that sinned, but cast them down to hell [tartaroo], and delivered them into chains of darkness, to be reserved unto judgment.” This place “tartaroo” (Strong’s #5020) only occurs once in the Bible and is translated “hell.”

UNTIL THE 1,000-YEAR JUDGMENT DAY. The two other words translated “hell” used often in the New Testament are “Hades” (Strong’s #86) and “Gehennah (Strong’s #1067). These words are entirely different than where the angels are being held until the Judgment Day. We would understand that the fallen angels were then restrained (but not with literal “chains”) in the earth’s atmosphere until the Judgment day. As a result, they have not been able to materialize as before—even until today. Peter tells us God’s judgment day is not 24 hours, but a thousand years. “But the heavens and the earth, which are now, by the same word are kept in store, reserved unto fire against the day of judgment and perdition of ungodly men. But, beloved, be not ignorant of this one thing, that one day is with the Lord as a thousand years, and a thousand years as one day” (2 Peter 3:7, 8). Some of the fallen angels, we would understand, will have repented having benefited from observing for thousands of years the sinful course of mankind.

FALLEN ANGELS TESTED IN THE JUDGMENT DAY. The features of the 1,000-year Judgment Day will open gradually open, beginning with the judgment of the nations and then the judgment of individuals of mankind. It is the same period during which Satan is bound (Revelation 20:1-3), so mankind will have a real opportunity to escape his blinding influence as god of this world (2 Corinthians 4:4). But it also opens with a time of trouble caused by spiritual as well as earthly forces resisting the setting up of Christ’s Kingdom. The fallen angels will, no doubt, also be tested being given ability to materialize again to determine whether they have really reformed and accepted God’s will and purpose for them or not.

Hope these thoughts weaving the scriptures together are helpful and reasonable for you to consider. Let us know if you have any questions, comments or would like us to go further on how we know when the Judgment Day starts.