Contract: The Phantom of Eldberg is a Skellige side quest with suggested level 17.

Completing this side quest can open up side quest "Stranger in a Strange Land", and then "The Cave of Dreams".

This quest can be picked up from the Arinbjorn noticeboard. Talk to Jorund for more information on the contract. You can also increase the reward amount by 41 crowns.

After talking to Jorund, head to the designated map marker to investigate the lighthouse. Once arriving, you'll be dealing with mulitple wraiths.

You will eventually come across the lone surviving lighthouse keeper, Mikkjal. After talking to Mikkjal he will give you a lighthouse key. Head outside and go investigate the lighthouse, you will encounter more wraiths along the way.

Just outside the lighthouse you can use your witcher senses to see some markings on it, and Geralt will determines its a curse, and what sort of monster he is dealing with.

You can head back at this point, or investigate the lighthouse further. If you decide to investigate the lighthouse, you will find a letter that shows the lighthouse keeper is the cause for the curse.

Head back to Mikkjal and talk about the Penitent. After talking to him and convincing him to light the lighthouse, you will be fighting the Penitent, but wont be able to do any critical damage until the lighthouse is lit. Use "spectre oil" as well as Yrden and Quen signs will make the fight alot easier.

After dealing with the monster, loot it, and then you can decide how you want to deal with the lighthouse keeper.

Return to Jorund to collect the reward.

Before you can exit the tavern, you'll have to kill some men to leave. As you leave the tavern, the father of the men you just killed and group of others takes you the the Jarl, Madman Lugos.

You will immediately be taken to the quest "Stranger in a Strange Land", in Madman Lugos's Dungeon.

Stranger in a Strange Land

Call out to the guard, and convince him to let you out and see Madman Lugos. After talking to the Lugos, he lets you go and wants you to help his son, in the quest "The Cave of Dreams".