(The only places that use them today are banks, Masonic lodges, and Mormon temples.)
Jacob explains how we become devils by using the devil's own secret combinations.
And our spirits must have become like unto him, and we become devils, angels to a devil, to be shut out from the presence of our God, and to remain with the father of lies, in misery, like unto himself; yea, to that being who beguiled our first parents, who transformeth himself nigh unto an angel of light, and stirreth up the children of men unto secret combinations of murder and all manner of secret works of darkness. 2 Nephi 9:9
And Nephi says much the same thing in 2 Nephi.
And there are also secret combinations, even as in times of old, according to the combinations of the devil, for he is the founder of all these things; yea, the founder of murder, and works of darkness; yea, and he leadeth them by the neck with a flaxen cord, until he bindeth them with his strong cords forever. 2 Nephi 26:22
Alma Jr. warns his son Helaman about them, saying that murders and workers of darkness use secret combinations.
For behold, they murdered all the prophets of the Lord who came among them to declare unto them concerning their iniquities; and the blood of those whom they murdered did cry unto the Lord their God for vengeance upon those who were their murderers; and thus the judgments of God did come upon these workers of darkness and secret combinations.
Yea, and cursed be the land forever and ever unto those workers of darkness and secret combinations, even unto destruction, except they repent before they are fully ripe. Alma 37:30-31
The robber Gadianton used secret combinations.
And it came to pass in the forty and ninth year of the reign of the judges, there was continual peace established in the land, all save it were the secret combinations which Gadianton the robber had established in the more settled parts of the land, which at that time were not known unto those who were at the head of government; therefore they were not destroyed out of the land. Helaman 3:23
The Nephites supported the robber Gadianton and his secret murders and combinations.
And it came to pass on the other hand, that the Nephites did build them up and support them, beginning at the more wicked part of them, until they had overspread all the land of the Nephites, and had seduced the more part of the righteous until they had come down to believe in their works and partake of their spoils, and to join with them in their secret murders and combinations. Helaman 6:38
The Nephites hanged the leader of the Gadianton robbers (Zemnarihah) and vowed to do the same to anyone else who uses secret combinations.
And their leader, Zemnarihah, was taken and hanged upon a tree, yea, even upon the top thereof until he was dead. And when they had hanged him until he was dead they did fell the tree to the earth, and did cry with a loud voice, saying:May the Lord preserve his people in righteousness and in holiness of heart, that they may cause to be felled to the earth all who shall seek to slay them because of power and secret combinations, even as this man hath been felled to the earth. 3 Nephi 4:29
Thus the Nephites put an end to the secret combinations.
And thus they did put an end to all those wicked, and secret, and abominable combinations. 3 Nephi 5:6
But they came back a couple chapters later.
the regulations of the government were destroyed, because of the secret combination. 3 Nephi 7:6
Now this secret combination, which had brought so great iniquity upon the people, did gather themselves together, and did place at their head a man whom they did call Jacob. 3 Nephi 7:9
Jesus burned the city of Jacobugath because of their sins and secret combinations.
That great city Jacobugath ... have I caused to be burned with fire because of their sins and their wickedness, which was above all the wickedness of the whole earth, because of their secret murders and combinations. ... Behold, I am Jesus Christ the Son of God. 3 Nephi 9:9-15
And in the year 260 CE, wicked people were using Gadianton's secret combinations again.
The wicked part of the people began again to build up the secret oaths and combinations of Gadianton. 4 Nephi 42
Someday the blood of the saints will cry out to God because of secret combinations.
And it shall come in a day when the blood of saints shall cry unto the Lord, because of secret combinations and the works of darkness. Mormon 8:27
So why do you use secret combinations?
Why do ye build up your secret abominations? Mormon 8:40
Secret combinations are the most abominable and wicked things in the sight of God.
They formed a secret combination, even as they of old; which combination is most abominable and wicked above all, in the sight of God. Ether 8:18
God doesn't work with secret combinations.
For the Lord worketh not in secret combinations, neither doth he will that man should shed blood, but in all things hath forbidden it, from the beginning of man. Ether 8:19
God will destroy any nation that uses secret combinations.
And whatsoever nation shall uphold such secret combinations, to get power and gain, until they shall spread over the nation, behold, they shall be destroyed; for the Lord will not suffer that the blood of his saints, which shall be shed by them, shall always cry unto him from the ground for vengeance upon them and yet he avenge them not. Ether 8:22
Ye shall awake to a sense of your awful situation, because of this secret combination. Ether 8:24
Omer lost his kingdom because of Akish's secret combinations.
And now I, Moroni, proceed with my record. Therefore, behold, it came to pass that because of the secret combinations of Akish and his friends, behold, they did overthrow the kingdom of Omer. Ether 9:1
The people rebelled because of that secret combination.
There arose a rebellion among the people, because of that secret combination. Ether 11:15
Many people were killed with the sword of those secret combinations
Wherefore, it came to pass that in the first year that Ether dwelt in the cavity of a rock, there were many people who were slain by the sword of those secret combinations, fighting against Coriantumr that they might obtain the kingdom. Ether 13:18
The brother of Shared (whose name was Gilead) received his strength from secret combinations.
Now the brother of Shared, whose name was Gilead, also received great strength to his army, because of secret combinations. Ether 14:8
Gilead's high priest murdered him while he sat on his throne. Then Lib, who was one of the secret combinations, murdered the high priest in a secret pass. (Lib, by the way, was the tallest man in the entire kingdom.)
And it came to pass that one of the secret combinations murdered him in a secret pass, and obtained unto himself the kingdom; and his name was Lib; and Lib was a man of great stature, more than any other man among all the people. Ether 14:10