The rebellious undead general can be found in the dunes southwest from the Ruins of Morah, so it's much closer to enter the Alkali Pan from there. Take the scepter that drops from the general and return it to Palawa Joko. The quest will update and now point to the hidden passage known as the Basalt Grotto. Head out into Joko's Domain and reach the entrance to Basalt Grotto (entry is not needed). Return to the Whispers Adept to claim your reward.