I interpret the wards this way,so mishaps do happen still. if they are not premeditated murder right? another scenario im curious how the near-mythal would handle it. A mage and his apprentice, the apprentice fails miserably at something and the mage looses his temper and casts a small spell to teach the apprentice a lesson, not to kill him. how do you think the near-mythal would react?
The schools of magic make and maintain portions of the wards that shield S'shamath. So they can also design spells which are exempted from the wards they made. Either through spell design or by designating a spell that shouldn't be stopped by the wards they control.
All the schools of magic therefore possesses spells which are which are not stopped by the wards. In case the other schools try anything in spite of the wards. Among these spells are methods to hurt students who annoy their teachers. These methods would be carefully guarded by each school, to avoid other schools or foreigners from being able to use that magic against them.
