* A healer who can elicit immune responses in the bodies of her victims (organ rejection), effectively causing their self-destruction.
* A serial killer magus whose only ability is projecting her voice and changing how it sounds, so she drives her victims to suicide by talking to them. Constantly. All the time. From every direction. Even from inside their own heads.
* A perfumer whose magecraft is changes a person's chemistry so it emits specific scents. So she makes her victims exude an odor that makes animals attack them.
* A magus who can mess with people's face recognition. So, if he wants to kill person X, he makes person Y hate him with murderous passion, and then makes it so that, to person Y, person X looks like himself. Or he just drives people mad by making their faces in the mirror look like the person they hate the most.
* A magus who can (somehow) make his victim believe he is in a Groundhog's Day loop, and thus can get away with anything.
* A magus who can (somehow) make his victim think itself and believe itself stronger/smarter/handsomer/whatever that it actually is, until it gets itself killed by biting more than it can chew.
* Thaumaturgical systems are rules embedded upon the World through a ritual and fomented by faith in their mystery. A certain clan developed a variation that allows for a lesser, simpler rule (for example, X must die) to be ingrained in a similar manner. The rule is eventually rejected by the World, but if it's simple enough and non-threatening to the World at large, by the time it is removed by the World, it has already achieved the desired effect.