The Witcher Bestiary - Striga
Striga Occurrence: A striga is a woman transformed into a monster by a curse; she is filled with hatred towards all living beings, devouring them gladly; a striga may tolerate necrophages; she needs a hideout during the day, often choosing a sarcophagus in a forgotten branch of a crypt.

Immunity: Resistant to steel.

Susceptibility: Sensitive to silver; a striga may be freed from her curse by those who survive a night near her sarcophagus.

Tactics: A striga is a very strong and agile creature, but not as resilient as she might seem; she attacks by surprise and tries to tear opponents to pieces without giving them a chance to fight back; near her sarcophagus, a striga is always stronger.

Alchemy: Striga heart.

'Where does it come from? Spells, magic?'

'I have no idea, sire. The Sages research these phenomena. For us witchers, it is enough to know that strong will may create them. We also like to know how to fight them.'

ĎAnd kill them?'

'Most frequently, yes. That is what we are usually paid for. Few want the spell lifted. People usually just want to be protected. If the monster has killed people, revenge may be another motive.'