From the journal
Geralt slayed the Howler without much trouble, yet killing such a fierce fighter might very well have proved impossible, had not its previous conflicts with its monstrous kin weakened it considerably. The lesson, I suppose, is that when two monsters fight, a witcher wins.
Here about the contract. Any idea what this monster is?
Naye, but proper huge it must be. Slaughtered no less than a dozen wolves
– Conversation overheard in Lindenvale
One is hard-pressed to name another area of our world more thoroughly riddled with monsters than Velen. There is one silver lining to this sad fact, however: the beasts living there must compete fiercely for hunting territory, meaning monsters often end up killing other monsters. An aggressive chort known as Howler went on just such a fratricidal rampage, tearing a pack of wolves to shreds before attacking and killing a fiend significantly larger than itself.
Howler was a truly fearsome foe. Each one of its blows was enough to kill - only heavy armor or the Quen Sign could protect one from mortal damage. Particularly to be avoided was its charge - and whenever possible, the monster was best attacked from the side.