Sacrifice ( cinematic trailer ) Sacrifice is the fourth cinematic trailer released by BioWare for the video game " " , and serves as a reveal trailer for the " " expansion . Released on June 16 , 2015 , the video depicts the story of Arcann and Thexan , twin heirs of Valkorion , Emperor of the Eternal Empire . The video , released at E3 2015 , runs at four minutes and twenty - three seconds . Synopsis . Years before the Galactic War , Emperor Valkorion of the Eternal Empire looks without any visible emotion at the cribs of his twin sons Arcann and Thexan and then walks away . Later , when the young princes have grown into teenage boys , they are playing in a field of grass , fighting imaginary foes together , with wooden sticks serving them as swords . Some time later , Valkorion oversees a quarterstaff sparring match between Arcann , Thexan , and several Knights of Zakuul . When Thexan notices Arcann being knocked down by one of his opponents , he rushes to help his brother , pushing one of the Knights away with the Force and defeating the rest with his quarterstaff . However , after Thexan helps Arcann back to his feet , the twins both notice their father leaving the site without saying a word . The brothers are both in a dark room later , where Thexan constructs and activates a lightsaber . With the forces of the Eternal Empire ready to commence attacks on both the Galactic Republic and the Sith Empire years later , Arcann and Thexan , now skilled lightsaber combatants , both kneel before Valkorion in his throne room , located in the Spire on the planet of Zakuul , and leave to lead the military offensive . Valkorion does not look at his sons during their departure , gazing instead through the throne room ' s viewport , at which Arcann is visibly disappointed . The twin princes proceed to personally lead the Eternal Fleet and the Knights of Zakuul on several attacks against the Republic and Sith forces on various worlds . The Eternal Empire forces defeat Republic trooper s and Sith Warrior s , and Thexan kills a Jedi on one such battlefield . Following the conclusion of a battle in a blizzard , the brothers communicate with their father via hologram , after which Arcann angrily knocks the holoprojector away with the Force . Arcann and Thexan then lead an assault on the Sith holy world of Korriban , where the Twi ' lek female Sith Darth Atroxa coordinates the defending forces . Arcann suffers grievous injuries in the fight , including the loss of his left arm , and Thexan comforts him while he has a prosthetic limb attached . Shortly thereafter , Arcann uses his newly augmented strength to kill several Sith warriors and Darth Atroxa herself , after which the brothers board a shuttle and leave the planet . When the twin princes arrive at Valkorion ' s throne room and present banner s and lightsabers of the defeated Republic and Sith forces as trophies to the Emperor , he once again shows no emotion and indifferently turns away from the brothers , which enrages Arcann to the point where one of his eyes starts to glow yellow due to the dark side of the Force , and he charges and jumps at Valkorion with his lightsaber drawn . However , Thexan telekinetically pulls Arcann away before he can land the killing blow , and the two brothers proceed to have a short lightsaber duel before the still enraged Arcann fatally injures Thexan . Realizing what he has done , Arcann cradles his dying brother in sorrow . Meanwhile , Valkorion has approached the scene of the brothers ' fight and extends his hand to Arcann , calling him " son " and inviting the prince to come with him . Behind the scenes . The 4 : 23 minute cinematic trailer for the video game " " , titled " Sacrifice , " was released on June 15 , 2015 .