"Possession" is part of a series of quests in The Witcher 3: Wild Hunt that help Geralt of Rivia decide who to back as the next ruler of Skellige. Occurring near the mid-point of the game, this quest tasks Geralt with sailing to Spikeroog in order to help Cerys an Craite discover the cause of the strange malady afflicting the island's leader, Udalryk.