Contrary to popular belief, monsters are not all alike. Like people, individual members of the same species can each have their own unique traits, preferences and weaknesses. A good example of this is the katakan which once fed on the inhabitants of Oxenfurt. Perhaps influenced by its close proximity to the hard-drinking student youth of the city, this vampire had developed a keen appetite for blood spiked with a hefty dose of hard alcohol – and also baubles and gaudy jewelry of all kinds.
The vampire had clearly thrived on its high-octane diet. It had grown exceptionally strong and gained the ability to regenerate lost life quickly, cause heavy bleeding with its claws and, if all that were not enough, meld into the air and appear again behind its opponent's back. Luckily the Quen Sign meant the witcher was well-equipped to defend against this surprise attack, and the Yrden Sign would let him catch the monster in a trap.
To bait the vampire, Geralt took note of its dietary preferences and seasoned his blood to match by loading up on cheap wine. This made it somewhat harder to aim his blows, true, but he still managed to defeat the beast – then had another battle awaiting him the next morning, this one against a powerful hangover.