Gestalt Ritual

The Gestalt Ritual was a ritual used by the demon Fedra to aid Dean Winchester in defeating the Last Calusa in Supernatural: Bone Key.

Procedure
The spell, being demonic magic, requires a reverse pentagram which the demon must sit within. The demon must slice open their palm and streak their blood on the cheeks of the person the spell is being used upon. The person the spell is being used upon must focus on something such as a happy memory to the exclusion of all else to ground them when the ghosts enter their body. Once the person is ready, the demon then chants the spell in an unknown language. After the spell begins, the ghosts will enter the targeted person who must use the thing they chose to ground them to gain control over themselves and all of the dead within them. Once they have control, they will have access to all of the spiritual energy belonging to the ghosts within them and depending on which emotion or instinct they choose to use, can direct that energy to different effects. The person the spell is used upon is also more vulnerable to emotional manipulation, especially if the spirits within them are highly affected by the emotion that is being manipulated within them.

During the ritual, the demon will be connected to the person the spell is cast upon through a line of spiritual energy no thicker than a fishing line. Prolonged use of the spell will burn out the demon's vessel, but once the spell is stopped, as long as its before the vessel dies, the burnout will disappear with no ill effects upon the vessel.