The Witcher Bestiary - Frightener
Frightener Occurrence: Frighteners are very rare; they come into being as a result of magical experiments; to create a frightener, a mage has to possess great power and a basic knowledge of mutation.

Immunity: Frighteners are immune to almost all effects.

Susceptibility: Sensitive to steel and silver; very sensitive to loud sounds at high frequencies.

Tactics: In combat, frighteners rely on their size and strength; they try to knock their opponents down and then deal a lethal blow.

Alchemy: Frightener's eye and claw.

The first mage to create a frightener was the infamous renegade Dagobert Sulla, a diligent student of the Zerrikanian masters of alchemy and the supervisor of the Trial of the Grasses carried out at Kaer Morhen. Upon beholding the abomination he had created, Sulla is said to have cried: ‘What have I done?' He destroyed the monster; his notes, however, survived.