Conclave of Northern Mages
Vanielle and Vilgefortz lured Yennefer back to Aretuza, where they informed her that Nilfgaard was planning to attack Cintra. Not that Yennefer cared. She only cared for finding Tissaia. To her surprise, Tissaia had no idea Yennefer was in Aretuza. Vilgefortz lied to Yennefer in hopes of convincing her to join their cause.
Vanielle was one of many mages who attended the conclave of Northern mages in Aretuza. Artorius, Stregobor, 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. Rather than watching them fall, Tissaia wanted to help Cintra defeat Nilfgaard. Vilgefortz, Sabrina, and Vanielle sided with Tissaia, wanting to convince 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, Nilfgaard had strengthened trade and funded research. Tissaia accused Fringilla of rejecting the order and way of life that took centuries to build. Fringilla retorted that they simply modified it. They've taken a new path, guided by the White Flame. Nilfgaard believed in shared sacrifice and that there was no such thing as dark or light magic. In taking Cintra, they had a chance of saving the continent. The mages put it to a vote. Unfortunately, most side with Stregobor and Artorius to allow Cintra to fend for themselves.
Battle of Sodden Hill
Approximately 60 mages, Vanielle, Vilgefortz, Triss, Yennefer, Tissaia, Coral, and Sabrina included, board a ship headed for Sodden Hill. They must get to the Elven keep that guarded it before Nilfgaard did. They had already sent word to the Northern kingdoms. Temeria and Kaedwen agreed to join them in defending the land. The plan was to protect the keep. Vanielle, Triss, Yennefer, Tissaia, Vilgefortz, Coral, and Sabrina arrived at the keep. The only thing separating Nilfgaard from the North. They were greeted by a man. Yennefer advised him to take the children and hide, but as he explained, there was no more hiding from Nilfgaard. Their only chance was to fight.
The keep was attacked by Fringilla and Nilfgaard in the late hours of the night. The sun had risen and the Northern mages made it through the night. Unfortunately, Nilfgaard arrived much sooner than they anticipated and the Northern armies were still a ways out. There were only 22 of them left, Triss, Yennefer, Tissaia, Vilgefortz, Vanielle, Coral, Atlan Kerk, and Sabrina included. They witnessed as a thick fog consumed the mountains around them, signaling Nilfgaard's encroachment. Vanielle was shot with several arrows during the attack and died.