The Lost Tomb was an arena and an ancient location in the Realm of Outworld. This ancient pyramid is also built as a huge mausoleum which rests the dead body of Outworld's legendary ruler known as Onaga the Dragon King, and it also housed the mummified remains of the king's undefeatable army.
This aged-old, pyramidal tomb contained the remains of the Dragon King's army which is consisted of loyal warriors who watched from the wings while locked in their stony prison after they ritualistically committed mass suicide since his death. In the distance behind the Dragon King's sarcophagus was a huge, bronze circular ring-like object with a striking resemblance of the Amulet of Shinnok. And what was written on the walls of this tomb as well on the king's sarcophagus is an ancient Edenian language inscribed by Onaga's holy men that was intended to bring back Outworld's long lost ruler from beyond the grave by returning his spirit to his original body. This huge mausoleum is located in the pyramid that is just outside the Sarna Ruins