Omega Weiss Omega Weiss is the final boss of " Dirge of Cerberus - Final Fantasy VII - " , fought in Chapter 12 . It forms when Weiss the Immaculate joins with Omega following his duel with Vincent Valentine in the Deepground headquarters below Midgar . Story . Professor Hojo , the former head of Shinra ' s Science Division , was killed by AVALANCHE , but before he died , he uploaded his mind onto the Worldwide Network . The network was fragmented during Meteorfall , locking his data away until the system was reestablished three years later by the World Regenesis Organization ( WRO ) . The digital Hojo scoured the world for a host body strong enough to fuse with Omega . His quest led him to Weiss , the leader of Deepground . Hojo planned to use Deepground and its military resources to procure the materials necessary to summon Omega and join with it to gain ultimate power . Using Weiss as his host , Hojo summons Omega , but in the final stage of his plan he is defeated by Vincent Valentine . Nero the Sable rouses his brother after Hojo ' s defeat , permeating him with impure energy and rendering Weiss unfit to fuse with Omega . This destroys Hojo ' s neurodata . Nero and Weiss join to form Omega ' s core , becoming " Omega Weiss . " Battle . Omega Weiss has many projectile attacks , but most can be shot down before they reach Vincent . If Vincent hides in an alcove he can dodge most of the attacks and still keep attacking the boss . Should both of these strategies fail , the missiles can either explode upon impact near Vincent , or hover in place as mines . The mines will self - destruct if the boss fires a new wave . At a certain point , crystal shields will form in front of Omega Weiss , and Weiss will break off from Omega to directly use sword combos against Vincent . Once the shields are destroyed , Weiss will return . They can even be destroyed before he has the chance to attack . However , if they are not destroyed quickly enough , they will fire at Vincent . There is also another variant , where a ring of shields orbits around Vincent before rushing at him . Omega Weiss may use his most powerful attack , Omega Meteor , which can deal well over 2 , 000 damage . This can be avoided by standing on a crystal platform at the edge of the arena . The battle may come to an end well before Omega can use this end - all attack , though a Phoenix Down should be used , just in case . Omega Weiss is invincible during this attack . After Omega Meteor , the boss glows orange and speeds up dramatically , releasing several attacks at once . This lasts for several minutes , but if not defeated , Omega Weiss will return to his normal coloration and attack pattern , with one new addition . Occasionally , it will " reseal " itself into the top - shaped form from its introductory cutscene , fly to a different spot on the arena , and reopen . This serves no apparent function , but it does make it temporarily invincible . Eventually , the boss may repeat the Omega Meteor phase . Strategy . This battle can easily be won by constantly assaulting Omega Weiss with the Death Penalty , a gun usable only when playing as Chaos . Each hit will deal either 1 , 000 or 1 , 500 points of damage . Hitting Weiss , who sits towards the top of the enemy , will deal a full 2 , 000 damage . Attacks . These attack names are derived from how the attacks themselves are described in the BradyGames strategy guide for " Dirge of Cerberus - Final Fantasy VII - " . Therefore , they are not necessarily the official names .