The blood of Jesus is a weapon that we as believers have against our accuser, the devil. Revelation‬ ‭12‬:‭10‬-‭11‬ ‭NKJV‬‬ says

“Then I heard a loud voice saying in heaven, “Now salvation, and strength, and the kingdom of our God, and the power of His Christ have come, for the accuser of our brethren, who accused them before our God day and night, has been cast down. And they overcame him by the blood of the Lamb and by the word of their testimony, and they did not love their lives to the death.”