The Truth Spell is a spell that was written in the Book of Shadows by a Warren witch who's name is unknown. The spell lets the person who casts it find out the truth from the people they talk to. After 24 hours, the truth is forgotten. Only the person who cast the spell will remember what was said.
When the spell is used for personal gain, it will go wrong and force the person who cast it to tell the truth. Also, it can spread beyond the person it was meant to hurt and affect anyone nearby.