The caster of this spell could target a creature near it and cause the creature to begin attacking its own self and do so in the most violent way possible. The caster chose one of the following two effects:

Cause the target to wield their own weapon (dagger, mace, fists, claws, etc) and begin violently attacking themselves in their own face.

If the target cannot use a weapon, then instead it begins to pound their face against the nearest hard surface (often the ground) with all of their might over and over, causing immense harm to themselves. If the target was wearing a helmet, it would uncontrollably remove it when the spell effect began.

Anyone attempting to help the target using their hands could get smashed and pummeled by the targets wild, uncontrolled swings.