After Sam Winchester rescued the soul of Bobby Singer from Hell as part of the second trial, he attempted to deliver him to Heaven. However, as Bobby's soul ascended towards Heaven, Crowley used this spell to capture him and try to take him back to Hell. As Bobby's soul descended towards the ground, Naomi intervened, causing the cloud containing the soul to stop descending. After Naomi drove Crowley off with her white light, she cancelled the spell and Bobby ascended into Heaven.
The exact procedure for the spell is unknown, but it causes the soul it is used against to be captured in a reddish cloud. Crowley was able to control the movement of the spell with his mind and Naomi was able to interrupt its movement when she appeared. Despite not being the caster of the spell, as an angel, she was able to cancel the spell with her powers.