Prerequisite: Complete "The Lord of Undvik" and "Possessed." | Suggested Level: 18
After helping both of Crach's children, return to his castle to be met by one of his associates, Arnvald - the decision of who'll be the next king is in progress. Follow him into the main hall to find Hjalmar and Cerys arguing. Head past them and toward Crach's chambers.
After receiving a sweet blade for your work from Crach, you'll hear a fight breaking out back in the hall. A trio of bears are tearing the place apart (no, seriously), so take them out quickly. After the brawl, you can go with Cerys or Hjalmar to figure out who's responsible for the massacre.
If you stay with Cerys, you'll need to use your Witcher Senses to figure out what happened. Examine the bear to learn that it's something of a were-bear, triggered by something the host drank. Check around until you discover the scent, then follow it to the source of the transforming drink. Take your findings to Hjort, the castle druid.
You'll then need to check the cellar for more clues. Follow her there and use your Witcher Senses to find the barrel holding the were-bear cocktail. Once you do, someone will set the cellar ablaze. Use Aard to bust away the barrels blocking the exit, then take the tunnel to safety.
Return to the cellar entrance to find footprints. These will lead you to a scrap of Arnvald's tunic. Hurry back to the main hall to find the murderer fleeing on horseback. Chase him down and knock him out of the saddle to learn the truth. The quest will wrap up after a pretty intense cut scene.
If you go with Hjalmar, you'll ride to a village where the tribe members may indeed be the were-bears in question. Use your Witcher Senses to check all around the village, then head for the shrine Hjalmar points out. Use your Senses here too to find a strange scent; this will lead you to an abandoned longhouse. Inside are some strange mushrooms… and a trapdoor.
Head down and explore the cave underneath the house to encounter a berserker named Halgrim. Hjalmar will initiate a fight, so take this dude out - he will enter his bear from at some point. Head further into the cave to find the head of this clan, a druid named Artis. Expect another fight here; Artis will even summon additional bears. Check his corpse after the fight to learn the truth. The quest will wrap up after a similar cut scene to Cerys' quest path.
Prerequisite: Complete "King's Gambit." | Suggested Level: 18
After solving the murder at the main hall, you can accompany Crach to see who will be crowned ruler of Skellige. If you helped Cerys, it'll be her. If you helped Hjalmar, it'll be him. Either way, it's a quick and easy quest.