Sarah has an array of powers, that I'm going to separate into a few different categories. In addition to the magic described below, she can use a dagger, albeit rather poorly.
Augmentation Magic:
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Augmentation magic was Sarah's official school of study, as she could never have openly studied Blood Magic in Starkhaven.
Heal: This simple spell stitches together torn flesh, repairs cracked bones, and generally puts things back together. If you aren't dead yet, this will help.
Rejuvenate: This spell makes fatigue and tiredness fade away in an instant, helping her allies stay in the fight. Or keep moving in the face of danger.
Ameliorating Aura: This spell releases a cloud of magical energy that, although it can be resisted, compels those in the vicinity to be a bit calmer, to stop fighting, and to just be friendly to each other. Doesn't get used much.
Blood Magic:
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Blood Magic is Sarah's true school of study, and she has managed to master it so far rather than letting it master her. It allows her to trade her own vitality for power, as well as affecting the blood of others directly.
Bloodstrike: Sarah uses some of her own blood as a series of projectiles. The expelled blood turns ridiculously acidic, and usually corrodes straight through anything short of steel.
Consumption: By magically draining blood from the fallen and the still-living in the area, Sarah can replace some of her lost blood. Some magical effect changes the blood type to hers, so she won't die from an impromptu transfusion. This works even on creatures that have extremely alien blood that by all rights shouldn't help her at all.
Cold as Ice: This ability freezes a person's blood in their arteries. This is usually not only excruciatingly painful, but paralyzing. On the upside, it's not usually lethal. Usually.
Puppets of her Will: By manipulating the blood in a person's body directly, Sarah has learned to literally take control of others' bodies. However, it doesn't work in the way one might think. Sarah has learned to raise efficiency by only affecting the blood in the brain, allowing her to take precise control of their motor functions. She can manipulate the recently dead in a similar manner, though in this case she manipulates the blood that exists in Bone Marrow instead. Manipulating the dead like this happens to be a very clumsy way to control a body, so her Pseudozombies aren't the best fighters.