Hunted by Renfri
Stregobor lured the witcher, Geralt of Rivia to Blaviken with the help of his servant, Marilka, to hire him to assassinate Renfri. Stregobor explained his reasoning behind wanting to kill Renfri. The Curse of the Black Sun marked the imminent return of Lilit — the demon goddess of the night — whose sole purpose was to exterminate the human species. Lilit's path was to be prepared by 60 women wearing gold crowns, who would fill the river valleys with blood. Stregobor studied the girls born around the Black Sun and found internal mutations among them. He tried to cure them, locking them in towers for safe keeping, but each girl died. He believed eliminating them was the lesser evil, though Geralt wasn't convinced.
Renfri, princess of Creyden and the daughter of Fredefalk, was after Stregobor. He personally delivered Renfri in the middle of the afternoon, under the Black Sun and knew for certain that she was the bringer of evil. In fear of Lilit's return, Stregobor dispatched someone to follow Renfri into the woods and kill her. However, they later found him in the brush with Renfri's broach jammed in his ear. She disappeared shortly thereafter and didn't reappear for another two years. Stregobor would have stopped her himself except for the fact that she's resistant to magic given her mutation. She chased Stregobor for years, plotting her revenge, and then she had tracked him to Blaviken. Despite Stregobor's offer and reasoning, Geralt only killed monsters, and refused.
Despite refusing Stregobor's offer, Geralt eventually ended up killing Renfri. Stregobor came down to see the destruction left in her wake, and he ordered Marilka to bring him a cart so that they could take Renfri's corpse back to the tower for an autopsy. When Geralt objected, Stregobor informed him that it was Renfri's mutation that allowed her to influence her followers. When Geralt refused to lower his sword, Stregobor realized that he must've been similarly influenced and directed attention to the men Geralt killed. This caused the townspeople, Marilka included, to revolt against Geralt. They threw stones at him, as Renfri predicted they would, until he left.
Years in the past, during Istredd's time under the Brotherhood of Sorcerers, Stregobor mentored him. Stregobor tasked Istredd with getting to know Yennefer in order to gain insight on her. From Istredd, Stregobor learnt of her elvish heritage.
Sending Yennefer to Nilfgaard
The Chapter gathered to discuss their concerns regarding Cintra turning down their mages. In fact, King Dagorad had banned mages from Cintra entirely. Stregobor had heard rumblings that the king was ill, and supposed that should he die, perhaps his heir, Princess Calanthe would be more inclined to accept their mages. However, Tissaia doubted she would. Artorius asked what of Nilfgaard, and Stregobor criticized King Fergus for squandering the kingdom's money on women while his people starved to death. Fringilla, Artotius' niece, would be in Nilfgaard by week's end, and Tissaia assured them that she would bring sanity and bread to the kingdom. However, Stregobor had little faith in her, so Artorius suggested sending someone with a bit more "spine" to Nilfgaard. Stregobor recommended Yennefer, since they'd be spitting in Dagorad's face to send her to Aedirn, Cintra's major trading partner. The only thing Cintra hated more than mages was elves, and Yennefer was a quarter-elf. Tissaia was very much against sending Yennefer to Nilfgaard, accusing Artorius of nepotism, sparing his niece of her duties. The chapter put it to a vote, and Yennefer was reassigned to Nilfgaard.
Stregobor, Artorius, Tissaia, and the rest of the Chapter gathered to initiate the new recruits into the Brotherhood, which Yennefer neglected to attend after being reassigned. However, she did show up for the Aretuzan ball completely transformed. King Virfuril discarded Fringilla in favor of Yennefer, and the two danced on the center floor with Stregobor, Artorius, and Tissaia watching disapprovingly.
Conclave of Northern Mages
Stregobor was among many mages to attend the conclave at Aretuza. He, Artorius, and Tissaia led the conclave. Artorius and Stregobor had no desire to go to war with Nilfgaard. Especially not for Cintra, who rejected their mages for decades. However, Vilgefortz worried that more kingdoms would fall after Cintra as Nilfgaard wanted the entire continent. Rather than watching them fall, Tissaia wanted to help Cintra defeat Nilfgaard by convincing the kings to send their armies because if they didn't stop Nilfgaard now, more kingdoms would fall.
Fringilla arrived at the conclave and denounced any suspicion that Nilfgaard was planning to take over the continent. Under their new leader, Emperor Emhyr var Emreis, Nilfgaard had strengthened trade and funded research. Fringilla believed that in taking Cintra, they had a chance of saving the continent. If the Northern mages wouldn't take sides, Fringilla asked that they at least stay out her way. Fringilla then pointed out that if not for Yennefer, she never would've been assigned to Nilfgaard, and it wouldn't be the empire it is today. Artorius joked that had they sent Yennefer to Nilfgaard as planned, It would still be a "shitty backwater." Yennefer admitted this was true. Instead of Nilfgaard, she went to a prized kingdom and did "fuck all for decades." She helped murderers and rapists keep their crown. If given an option, she'd vote to burn it all down. The mages put it to a vote. Unfortunately, most side with Stregobor and Artorius to allow Cintra to fend for themselves.
- It appears that the show's Stregobor is a combination of two distinct book characters: Stregobor, a Kovirian mage who wants to prevent the Black Sun, and Gerhart of Aelle, the rector at Ban Ard Academy and one of the oldest mages of the Continent.