With the key in your possession, Surt asked you to find the secret passage to Adma Stronghold and infiltrate the cursed place. He sent you to Sahnu, a Seiren living near Nahor Lake. Sahnu used a Waterdrop of Spirit to create Ribbit Essence to help you get through the narrow passage. Once you were inside Adma Stronghold, you found it had been overrun by the undead, and everyone had succumbed. Villaire, a Red Sky Legionary, had become a young child. You were forced to kill him, and when you did a strange seed-like object came out of his body. You reported the events to Heintz, who explained that Beritra must have been behind it. He surmised that the seed was the source of Brusthonin's contamination. He had you inform Sigyn of all that happened.