Enter Cove of Decay and kill The Octagorgon. After doing this you can swim to the ocean floor and you will find some interactive chests on the ground. Inside one of them, you will find a Partially Digested Hand. Only one person has to do this.
Once you have the Partially Digested Hand, you must head onto the beach and you will find a firepit. The person who has the hand can interact with the remains in the Firepit. This will spawn a level 31 ^^^ Epic x 2 mob, Captain Ulssissaris. Kill him and the quest will update.
Head to the Ruins of Varsoon and examine an interactive book on a table in the workshop of the enchanter (+263, 0, +118).