Dorian's Diary is a quest item need to trigger an encounter with a werewolf in the enhanced version of The Witcher 2: Assassins of Kings.
Location and Acquisition
During the quest Lilies and Vipers in Chapter III enter the forest cave system and make your way to the far northwest corner. Among the scattered papers, you will find Dorian's Diary and learn of his uncertain fate. Dorian was a sorcerer's apprentice and his master commanded him to observe the wolves during mating season resulting in poor Dorian getting bit. He notes the herbal remedies are not helping, but his other senses are becoming keener.
The bite wound festers and burns like fire. Poultices are of no help, yet I still trust in the beneficial effects of herbs. I am unsure whether to remain here and continue looking for healing plants, or whether to seek aid in the city. The idea observing the habits of wolves in mating season was one of the most idiotic my master ever had, may he rest in peace. And it highlights one of the problems plaguing the educational system: in studying magic one must fulfill the whims of senile old men.
I think I smell sausages. Strange as it is, it seems my sense of smell has improved. Maybe hunger has sharpened my senses? Today I managed to spot and sneak up on a hare, while usually I would not spot one even if it kicked me in the arse. Hmm, garlic? I think I shall go out and see if there are humans nearby. The moon is full and so bright that I will not lose my way.