Back to Skellige
This quest can be started by reading the notice board in Rannvaig or by travelling to the southeast and speaking with Lothar at his hut.
When you speak to Lothar he’ll tell you that someone planted a deadly curse outside his house in the form of a Nithing. Geralt will reveal two ways to deal with it. Either get the caster to remove the curse or Geralt can reverse the curse and send it back to the caster.
Examine the Nithing using your Witcher senses and then follow the tracks to a Skellige Shawl. Geralt picks up a scent so follow it back to Rannviag. The scent fades away so you’ll need to ask around to find out who the shawl belongs to.
During the daytime you’ll find an unnamed woman near the harbor. She’ll tell you that the shawl belongs to a herbalist called Jonna.
Speak to Jonna and she’ll tell you that she cast the curse out of revenge. She was with Lothar for 10 years until he left without a word and found someone else. She will agree to remove the curse for a price. The price is that Lothar must denounce his son.
Return to Lothar and let him know about the deal who is not happy about it as it would mean casting out his son and wife. He demands you reverse the curse. You have the option to insist he denounce his son or to turn back the curse towards Jonna.
Assuming you turn the curse around walk up to the Nithing and interact with it. Geralt will carve Jonna’s name onto the shaft and turn the skull around to face her. Talk to Lothar to let him know the job is done.