Mantella The Mantella was the heart of Wulfharth , the Imperial Battlemage Zurin Arctus or a merging of both , and its acquisition is the final objective of . The item is described as a green jewel of unusual size , and was the energy source Tiber Septim used to power the Numidium in the absence of the Heart of Lorkhan . Associated quests . Journey to Aetherius . Meet with Nulfaga , in the castle Shedungent , to be teleported to the Mantellan Crux and retrieve the Mantella . History . Origins . Whether or not the Mantella was the heart of Wulfarth or Zurin Arctus is debatable , but most sources seem to point to it being Zurin ' s heart . The Mantella , in a basic sense , was a massive soul gem , in which contained the life force and soul of either Zurin Arctus or Wulfharth , both of whom were betrayed by Tiber Septim . It was used as a replacement for the Heart of Lorkhan to power the Numidium , which was utilized by Tiber Septim to conquer all of Tamriel , and destroy all those who did not entirely accept his reign . The Numidium was eventually demolished by the Underking with its remains scattering and the Mantella being blasted into Aetherius , to be lost for centuries . Without the Heart , Wulfharth falls into a state of semi - slumber , and the Blades began the painstaking task of recovering all of the Numidium ' s lost pieces , while the Underking ' s agents search for the Mantella . Events of Daggerfall . After many generations , the Blades were able to recover and rebuild every piece of Numidium , lacking only its power source which could not be found . However , in the year 3E 401 , the sorceress , Nulfaga , discovered the location of the Mantella within the Aetherial realm known as the Mantellan Crux , while on one of her astral travels . Seeing the benefit this discovery could have , Nulfaga sent a letter to the Emperor , Uriel Septim VII , promising to disclose the Mantella ' s location to him as long as he agreed to never use the Numidium to hinder the power of her son , Lysandus , or his Kingdom . Uriel Septim , not fond of blackmail , refused her offer and instead schemed to find a way to gain the information from Nulfaga without accepting her deal . After reacquiring the Totem of Tiber Septim , the Agent of Daggerfall was sent a message from Nulfaga stating that she would give him the location of the Mantella . Once the Agent arrived at Shedungent , Nulfaga teleported him to the Mantellan Crux where the Mantella was freed from its prison . The Mantella was then used to power the Numidium , allow the Underking to die , and turn the King of Worms into a god , in the Dragon Break known as the Warp in the West . More information . Whether or not the Mantella was the heart of Tiber Septim or Zurin Arctus has been debated . Obscure mythology reasons that the Mantella is the " Heart of Tiber Septim " because Tiber Septim himself was born through the merged dichotomy of the individuals Zurin Arctus and General Talos who joined as one to unite Cyrodiil and its people . In this sense , the Mantella forms as a representation of this union . Some believe the " Mantella , " rather than referring singular object , is actually a re - creatable process first attempted by Kagrenac during the creation of Anumidium , being dubbed a " " Crux of Transcendence . " " It has been said that the Tools of Kagrenac were actually built for the purpose of creating a Mantella , the reenactment of Lorkhan ' s sundering through the manipulation of mythical symbolism . By this belief , a Mantella , when created by Elves is more appropriately referred to as a " " Mer " tella . "