The Witcher Bestiary - Werewolf
Werewolf Occurrence: Werewolves are lycanthropes, which means that they are shapechangers; humans transform into werewolves as a result of curses; the creatures lurk near human settlements.

Immunity: They are resistant to steel and most effects.

Susceptibility: Sensitive to silver.

Tactics: They attack with fury and like to be on the offensive, confident of their resistance to conventional weapons.

Alchemy: Werewolf Fur.

Baron Wolfstein buried his face in his hands. His heart was throbbing. Suddenly the scent of his wife's blood and the blood of his children intensified. The baron's body swelled as his muscles grew, his noble attire fell in tatters on the marble floor. ‘My beloved, you... you are so hairy. You are a werewolf!' Bianca went pale. ‘What about our love?' In reply she heard a terrifying roar. Danielle Stone, The Curse of Baron Wolfstein and Other Love Stories