Hidden within the sunken Pyramid of Savathûn’s Throne World lies the Vow of the Disciple. Ancient symbols line its halls, telling a story of devotion, conquest, and betrayal. As Guardians step inside, they enter the domain of Rhulk, the first Disciple of the Witness, where Darkness is not merely wielded—but worshiped. To survive, fireteams must uncover the truth etched into the walls before the Pyramid claims them as its own.