The magic of the mind maps fairly well to the domain of psychology. It involves matters such as motivation, influence and perception.
The most common mindmagic, familiar to everyone, is the magic of oaths, vows and geasa, behavioural bindings which are very difficult, though not impossible, to break. They create a powerful mental pressure to keep them, comparable to an obsession, compulsion or addiction if you are trying to break them, or a very powerful positive motivation if you’re not. Marriage oaths are the most common – marriage is referred to as “oathbinding” and one’s spouse as one’s “oathmate” – but oaths are also taken between master and servant, liege and vassal, close friends, even members of military units. There is often a physical focus or token for the oath, typically a finger-ring, though the military use arm-rings on the upper arm. Military arm-rings can be spelled to identify that the wearer is bound by a loyalty vow, and anyone from the rank of sergeant up who has taken the same vow will be sufficiently trained in mindmagic to be able to detect this from a distance of three or four paces.
An oath of lifebond requires two witnesses and a "person of standing" to officiate, as well as the oathtakers (see Oathbond Ceremony), but a loyalty oath between master and servant requires only one witness and no officiant. Rings may be exchanged for loyalty oaths as well as for lifebonds.
For oaths of alliance and allegiance the ring is worn on the right hand, for love and friendship on the left (the heart side). Coppers/Earthists often make their rings out of wood, and put them on prior to the oathbinding ceremony, while Silvers/Golds/Asterists make them out of metal (or rather, have dwarves do so for them) and put them on after making their vows.
A well-made oath, with the assistance of a competent mindmage, added to familiarity and genuine emotion, gives the participants in the oath an enhanced sense of each other. They can’t read each other’s thoughts, but providing they’re reasonably nearby they’re aware of each other’s strong emotions and approximate physical location, even if they’re not able to see or hear each other.
Similar to an oath is a geis. The difference between the two is that an oath is between two people, mutually agreed on and binds both of them, while a geis is imposed by someone in authority on another person, and binds only the recipient. The person who receives the geis must acknowledge the authority of the one who imposes it, and must be able to perform the action of the geis, and consent to it, even if reluctantly. Geasa may include aversions or actions which are forbidden as well as actions which are required.
A vow is like a self-imposed geis. It is often, but not necessarily, witnessed by another person.
An oath is often recorded on a beautifully drawn and calligraphed piece of paper, with geometric figures corresponding to the magic of the oath and recording it. These papers are typically produced in triplicate, and the two parties to the oath and the witness each keep one. The parties and the witness sign them, mark them with their personal seals or the seals of their rank or position (if they have any – typically this is something only a Gold or a wealthy Silver will have, unless they are a Gryphon Clerk), and thumbprint them. The act of doing so, along with the oath itself, produces a record on the paper that can be read by anyone who has any skill in mindmagic to verify that the oath is a true oath. Among illiterate Coppers, oaths are usually verbal unless they go to a scribe and pay to have an oath recorded.
The seals (gold for a Gold, silver for a Silver) are themselves bespelled for this purpose.
Another form of mindmagic is parallel to charisma. All natural leaders and influencers possess an aptitude for it, and if trained can enhance it and so increase their authority. The elves did not reveal everything they knew about this form of mindmagic to their human subjects, and it is not as well understood, or as effective, as oaths and geasa.
The elves also possessed the knowledge of “glamour”, which is a form of mindmagic which influences the perceptions of those around the mage, in the mage’s favour. This art is considered lost.
The final category of mindmagic crosses over with lifemagic, and is the use of trance states to perceive the world differently or to control one’s body processes. This knowledge is mostly preserved among shamans of the peasants’ Earthist religion, though the upper classes have kept the knowledge of sleep induction (through the Three Rituals of Sleep) and a form of learning trance.
University-trained practitioners of mindmagic wear bracelets (etc.) of black wood, often elaborately carved in the case of the more advanced mages. Shamans wear only a single piece of cloth and are marked with a magical picture of their beast totem and (for full shamans) their plant totem, received during an ordeal of meditation.
A magistrate is often also a mage-minor in mindmagic, or employs one. They can observe an oath, vow or geis taking effect for about 20 people at a time.