When I saw the trailers and listened to the devs I thought that they were gonna act like some sort of protection from other spellcasters who could cast spells on you. While they do protect you from death from for example overcharge the spellcasters does not seem to cast spells on you randomly.
I kinda hoped that they would act as a shield all the time and make you be careful about dueling and interacting with other spellcasters so that there was a sense of danger with walking around in the magic realm which would also prevent you from leveling up too quickly.
Doesn't sound impossible to do with mods actually, if casting spells are the same as any action, maybe you could add so they cast spells on each other autonomously.