The Witcher Bestiary - Royal Wyvern
Royal Wyvern Occurrence: Royal wyverns are larger and more aggressive than their common cousins; they live in the wilderness, often in the mountains, as they like to build their nests on precipices; they attack any creature entering their territory.

Immunity: Resistant to stun attempts, immune to poison and generally fearless.

Susceptibility: Sensitive to silver and Ornithosaur Oil.

Tactics: They dive at their opponents, try to knock them down and poison them with venom; they are more clever than common wyverns and thus harder to defeat.

Alchemy: Toxin and wing membrane, venom glands.

The female royal wyvern is smaller but more cunning and venomous than her male counterpart. She can be aggressive towards both males and other females. She is a perfect example of how gender relations among humans have their source in the animal world. This is altogether not surprising.

- Master Dorgeray, Against the Institution of Marriage