The Decapitation Spell is a spell that magically decapitates a victim.
As part of his effort to stop the Winchesters from completing the Trials of God, Crowley began targeting everyone that they had ever saved. Crowley first targeted Tommy Collins, a young man who had once been saved from a wendigo by the Winchesters by using this spell to magically decapitate Tommy.
While the exact procedure is unknown, the spell is shown to start by causing the victim to hear his or her worst fear. The victim then grabs their head in extreme pain while blood streams out of their ears. Blood then starts streaming out of their eyes which bulge out slightly, indicating an increasing pressure in the victim's head. The pressure eventually increases to the point that their head explodes, violently decapitating them.