1. Avoiding ones garments being stained by the blood of the wicked
A couple of examples include Ether 12:38
all men shall know that my are not spotted with your bloodand Jacob 1:19
by laboring with our might their might not come upon our garments; otherwise their blood would come upon our garments, and we would not be found spotless at the last day
2. Washing ones garments in the blood of Christ
Lord_Wilmore has given a few examples here. There are several others, for instance, Christ himself speaking to his disciples in 3 Nephi 27:19
And can enter into his kingdom; therefore nothing entereth into his save it be those who have their garments in my blood
These two ideas may seem a contradiction. In one case the blood causes stains and in the other it cleanses. It almost seems a bit absurd to make garments white with blood as e.g. Alma 13:11 suggests. But as discussed previously, white is symbolic for pure in a spiritual sense and often connected to entering into and keeping covenants. This leads us to the covenant people of Israel who were commanded to perform sacrificial rites as a foreshadowing of Christ. For instance in Exodus 29:21
And thou shalt take of the blood that is upon the altar, and of the anointing oil, and sprinkle it upon Aaron, and upon his garments, and upon his sons, and upon the garments of his sons with him: and , and his garments, and his sons, and his sons’ garments with him.The sacrificial blood on the altar represented the blood of Christ. When it was sprinkled on Aaron and his sons and their garments, they were hallowed. When the blood was from other people, literally or figuratively, they were stained. This contrast is particularly evident in Alma 5:21-23, where the blood as symbol changes its meaning entirely from one verse to the next
The Hebrew word for blood may help understand the symbolism. The word is "dam", which is the same root as Adam/mankind. (Remember another word from this root was "adama"=earth). So these words are connected. In Jewish tradition, blood is regarded as the lifegiving substance of man and therefore sacred. Leviticus 17:1021 I say unto you, ye will know at that day that ye cannot be ; for there can no man be saved except his are washed white; yea, his garments must be until they are cleansed from all stain, through the blood of him of whom it has been spoken by our fathers, who should come to redeem his people from their sins.22 And now I ask of you, my brethren, how will any of you feel, if ye shall stand before the bar of God, having your garments stained with and all manner of ? Behold, what will these things testify against you?23 Behold will they not that ye are murderers, yea, and also that ye are of all manner of wickedness?
For the of the is in the bloodwhich was also a reason why consuming blood was prohibited according to the law of Moses. Also, the "shedding of blood" was a grievous sin and the blood-stained garment was a symbol of guilt.
The difference between the stains of blood and the cleansing of blood lies perhaps in the taking of life and the giving of life. Christ layed down his life voluntarily to pay the price for our sins. Interestingly, the plural for blood, "damim" is the exact same word as "money". Christ's shedding of his blood pays for our debts. As one of many paradoxes in the gospel, blood can either stain or cleanse, depending on whose blood it is and how it got there.
As a side note, we see the same kind of paradox when it comes to the consumption of blood. As mentioned earlier, it was prohibited under the law of Moses. But then Christ says in John 6:53-56
No wonder the Jews were offended.53 Then Jesus said unto them, Verily, verily, I say unto you, Except ye the flesh of the , and drink his blood, ye have no life in you.54 Whoso eateth my , and drinketh my , hath eternal life; I will him up at the last day.55 For my flesh is meat indeed, and my blood is drink indeed.56 He that eateth my flesh, and drinketh my blood, in me, and I in him.