Contract: In The Heart of the Woods - Skellige
Area: Skellige
Location: Fayrlund
Quest Giver: Fayrlund Notice Board
Other Requirements: N/A
Much like every contract quest there are two ways for you to start this one. First of which is be picking up the notice from the Fayrlund Notice Board and then speaking with the people arguing outside of town. Alternatively, if you stumble onto the people outside of town first then you'll begin this quest when you approach and speak with them.
Note: This quest has two drastically different endings; If you choose to side with Harald for this quest you'll miss out on the Woodland Spirit Achievement as well as the Ancient Leshen Mutagen.
For this quest you'll have to travel over to Fayrlund where you will find a large group from the town arguing in the quest area to the south. There will be a scene and some dialogue immediately upon approaching them. When the dialogue is over you'll have to explore the woods to determine the creature we're up against. There are three things that you are looking for:
1. Dead dog
2. Body pinned against rock
3. Scratches on rock near the white wolves
Once you've found them all your quest will update and ask you to read your Bestiary to learn more about Leshens/Woodland Spirits. They're under the Relict tab. Now you have two choices, you can either side with Harald or side with Sven. Siding with Harald means you will not be killing the Leshen and you'll not only be missing out on loot but leaving a very dangerous monster alive.
Depending on who you side with the outcomes are drastically different for this quest, the best outcome is from siding with Sven.
Side With Harald
Go out to the altar in the woods and five white wolves will spawn, loot the wolf hearts from them and place them upon the altar. There will be a cutscene of the Leshen accepting your pack, now return to Harald and tell him of your success. Sven will approach you with the other young men in the village and say that he has killed off the other elders and Harald is next.
You can choose to protect Harald if you wish, he can still die during the fight if you're not careful though. Alternatively you can let Sven kill Harald and avoid getting in the way if you wish too. Either way the quest will conclude here.
Side With Sven
If you side with Sven the first thing you will need to do is find the marked person in the town. Geralt mentions having to use his Witcher Senses but just look around for the house with Crows flying over head, if you've already fought a Leshen this should ring a few bells. Once you've discovered it's Hilde that is the marked one return to Sven and fill him in.
Now you'll need to go out into the woods and destroy the 3 Leshen totems before you're able to fight the Leshen. Two of the totems will be protected by wolves but it's easy enough to defeat them. If you're playing on a harder difficulty be prepared for this upcoming fight, you'll start the fight against four wolves and the Leshen.
Leshen Weaknesses: Dimeritium Bomb, Relict Oil, Igni
When you return to town you'll learn that a massacre happened in your absence. Say whatever you'd like to Sven, you get your coin and the same reward either way and the quest will now be complete.