The most notable to many readers despite the unrelenting Grimdark fantasy setting will be when Ciri gives herself up to Vilgefortz at Castle Stygga. He chokes and fondles our heroine like a doll before discussing the horrific experimentation he will subject her to all the while hyping himself up into an astonishingly terrifying A God Am I speech. Since he's been a picture perfect stoic villain in all his other appearances, this sudden turn to prancing maniac proves that he was always completely amoral and bat-shit insane despite the excellent Faux Affably Evil mask he presented to Geralt.
He wiggled his fingers in front of her eyes and suddenly grabbed her face violently. Ciri cried out and tried to escape, but he held her firmly. Her lips trembled. Vilgefortz saw this. "Child of Destiny," he laughed, and from the corners of his mouth dripped foam. "Aen Hen Ichaer, the Elder Blood... is now all mine!"
Vilgefortz's description of the, ahem, insemination procedure and the subsequent vivisection will turn your bowels to water and deserves its own bullet point.
The fact that both he and Bonhart want Yennefer to be Forced to Watch her foster daughter undergo this nightmare as well.
What Ciri went through after she was beaten by Bonhart at their first fight, beginning with being forced to watch as he severed the heads of her gang.
Earlier in The Lady of the Lake, we get the dubious pleasure of Ciri's run-in with the hermit simply known as Gramps. Anyone who's played the first game before reading the saga will find themselves hoping he's not like his similarly-named counterpart; who (claimed) he only cannibalized the dead and dying in the Vizima forest swampland. Well, those of us who wished it were dead wrong. He's far worse.