Contract: Strange Beast, which deals with a nasty little Nekker nest, is a Skellige side quest with suggested level 16.

You can start this quest in Larvik, which is the village east of Lofoten on the small Skellige island to the east. Talk to Thorleif in Larvik for more information on the monster, as well as increasing your reward.

After talking with Thorleif, talk to the warriors in the village about the monster.

Head to the ambush site and examine the site with Witcher Senses.

There will be a dead body by the cart, as well as some clay that looks like blood on the cart itself, on the opposite of the road there will be a blood stain, and near the stain, a set of prints leading into the woods. The prints lead into a cave.

In the cave you'll encounter the poisonous clouds again that can be temporarily removed with Igni sign. You'll also find lots of Nekkers in the cave.

Once in the main area of the cave, the Nekker leader, Hagubman, will arrive, which is a little tougher than the rest. Every 1/4 or so of health you remove from him, he will hide and spawn his Nekker minions. Remember, Nekkers are ogroids -- so don some oil and start slashing.

After dealing with him, loot the corpse, and return to Thorleif to collect your reward.