This ritual wipes clean the memories of another creature. The target becomes partially amnesiac, retaining basic, common knowledge, but nothing personal. The ones performing the ritual can author new memories to replace the stolen ones, if desired. Doing so is a fantastic way of hijacking someone's loyalty.
The Brainwash ritual is rather simple, and requires only a small blood offering of a participating mage, and that the target remain bound, blindfolded, gagged, and lying on a flat surface while the ritual is performed.