Werewolf's Wrath

"It was determined ages ago that a potion containing the fur of a werewolf could strengthen a witcher's mutations and augment his predatory instincts. Opponents of this potion's use argued that it made witchers similar to monsters. As a result, use of Werewolf's Wrath was restricted, though few objected since acquiring the beasts' fur is risky business."

When imbibed, Werewolf's Wrath, a mutagenic potion, provides access to a special enhancement of the Dexterity attribute; this upgrade awakens a witcher's predatory instincts and increases his fighting abilities after dark.