The crown of thorns is one of the Instruments of Passion that was placed on the head of Jesus during the events leading up to the crucifixion of Jesus. A divine item that was employed by Jesus' captors both to cause him pain and to mock his claim of authority.
Jesus endured hours of torture, Roman style. Flogged by the cat of nine tails, blindfolded and beaten, spit on, struck in the face, lacerated on nearly every part of his body. The prophet Isaiah spoke well when he declared that "his face was so disfigured he seemed hardly human, and from his appearance, one would scarcely know he was a man."
Then, as a last act of humiliation against Jesus, the Roman officers twisted a crown of thorns and placed it on his head. Taking up the reed they had given him as a mock scepter, they repeatedly struck him in the head with it. Then they bowed in mockery to the King of the Jews, and led him away to be crucified.
As a result of the pain caused by the crown of thorns, God cursed the ground, declaring that it would forever produce thorns and thistles. The crown of thorns represented that part of the curse that Jesus took upon himself in his crucifixion. There truly was no part of humanity and its ruin that he did not experience. And yet, though Jesus suffered for a time beneath the curse, his death and resurrection paved the way for those that believe on him to be set free from the power of sin. At his ascension, Jesus took his rightful place, seated at the right hand of God. The Roman soldiers may have inaugurated him in mockery, but Jesus truly was a King.
Being a divine instrument it can also be used as a weapon the combat the forces of darkness. However, once worn the crown causes severe anguish but in return it imbues the wearer with great divine power, mostly the power to conjure an endless amount of thorny vines that have the ability to cut down and destroy any unholy being. Unfortunately, the pain that the crown causes is the least of the wearer's problems, for when they adorn the crown, they begin to lose their sanity and simply act on their primal instincts due to their diminishing sanity.