Rience

From Witcher Wiki

Rience is a mage of considerable skill who is sent after Ciri in the novel "Blood of Elves". He is not as powerful as his master, Vilgefortz. In his quest to find her, he captures and tortures Dandelion to get information. If not for the extremely timely intervention of Yennefer, Dandelion might not have survived to continue his role as Geralt's frequent companion.

Yennefer's rescue of Dandelion leaves a permanent "impression" on Rience. While the mage does manage to escape with his life, the sorceress' final spell leaves the left side of his face permanently disfigured. Making him rather easier to track.