Why will Christ make a full end of all nations? To stop the shedding of the blood of the saints.
D&C 87:6 And thus, with the sword and by bloodshed the inhabitants of the earth shall mourn; and with famine, and plague, and earthquake, and the thunder of heaven, and the fierce and vivid lightning also, shall the inhabitants of the earth be made to feel the wrath, and indignation, and chastening hand of an Almighty God, until the consumption decreed hath made a full end of all nations;
7 That the cry of the saints, and of the blood of the saints, shall cease to come up into the ears of the Lord of Sabaoth, from the earth, to be avenged of their enemies.
This is the same thing we read about here:
Revelation 8:3 And another angel came and stood at the altar, having a golden censer; and there was given unto him much incense, that he should offer it with the prayers of all saints upon the golden altar which was before the throne.
4 And the smoke of the incense, which came with the prayers of the saints, ascended up before God out of the angel’s hand.
5 And the angel took the censer, and filled it with fire of the altar, and cast it into the earth
A censer is something to hold incense. The angel comes with “much incense” to offer with the prayers of all the saints. The much incense being offered with the prayers is the great righteousness of these saints. That is what makes it their prayers come up to god with such a pleasing scent. The response to the prayers tells us what they were praying for. It says the angel took the censer and filled it will fire of the alter, and cast it into the earth. The answer to the prayers is great destructions sent down from heaven. Thus the saints were praying for deliverance from the persecutions of the wicked.
The “consumption decreed” referred to in D&C 87:6 is not limited to the destructions when this angel blows his trump. Rather, they are the entire lot of the destructions in the Revelation of John taken together.