This form was created when Dante acquired the Soul Stone and it revealed to him that even with four of the Infinity Stones they wouldn't be able to beat Ultron Sigma, so he opted to go rouge and do it his way. Dante shows up for the final battle and actually outsmarts Ultron Sigma into using the Soul Stone which Dante handed over to him prior. When Ultron Sigma attempted to use it to enslave his enemies his fusion became more unstable as Dante informs him that only a noble soul can bare and use the Soul Stone. Ultron Sigma then uses the full power of their two stones to mutate into Ultron Omega after his use of the Soul Stone breaks their merged form. This ultimately cures the Sigma Virus and removes Ultron Sigma's immortality, which allows the heroes to use the Infinity Buster to destroy the fused villains.
Ultron Omega's body consists entirely of Sigma's deformed head as he was seen in the intro stage of Mega Man X5, with Ultron's upper body sticking out from its top, resembling Ultron-6's body. There are four limbs floating above them: two claws and two fists, the latter resembling the fists used by Sigma's final form in X5. Sigma's head, which is slightly damaged, holds the Space Stone on its forehead and a cannon inside its mouth.
Ultron Omega is an unplayable boss working similar to Galactus and Abyss: a giant boss that takes over its own half of the screen to itself. It has its own unique health bar like Galactus, and it can't be unlocked and used by the player like Abyss.
Ultron Omega occasionally summons Ultron Drones and will sometimes back out and summon more Drones. Ultron Omega has possession of two Infinity Stones: Reality and Space, which it can use alternatively. Once one of the Infinity Stone's Storm is used, it goes to the other Stone and back. Ultron Omega can fire three tracking projectiles when in possession of the Reality Stone instead of one. The Ultron half can also throw its claws at the player as well as attack with a flurry of energy beams from its palms. When enough damage is dealt Ultron Omega will put its hands in front in order to block damage. Attacking its hands enough will force it into a stun state where it takes triple damage.
Ultron Omega has two Hyper Combos and a level 3 Hyper Combo:
- Its first Hyper Combo has Sigma fire a large energy beam from the blaster cannon on its mouth.
- Its second Hyper Combo requires Ultron Omega to have its two pairs of hands together. Ultron Omega grabs the opponent, and then traps them in a paralysis bubble. Ultron's Omega's fists and claws attack them, slam the opponent into the ground, and then finish them with a downward attack by Ultron's claws similar to Wolverine's Drill Claw.
- Its level 3 Hyper Combo is an enhanced version of its level 1 blast attack, in which both Infinity Stones are used to channel a powerful beam of energy that can dish out almost full damage to any character.
Marvel vs Capcom: Infinite Edit
- "Good, evil... We have transcended such... limited concepts." (Story Mode final battle)
- "You shall feel our wrath! KNEEL BEFORE YOUR GOD!!!!!" (Story Mode final battle after saving Dante)
- "Do you think...you can...defeat us?" (Arcade Mode final battle)
- Dante, Where are you going? We must return the favor. (Story Mode)
- We Cannot be destroyed, we are perfect.....WE ARE ULTRON OMEGA!!! (Story Mode)
- "Contemptuous fool, we will erase you!" (Level 1 Blaster Hyper Combo)
- "Hahaha, how about this one?!" (Level 1 Blaster Hyper Combo)
- "Let's test your defenses!" or "You fight aimlessly like a worthless animal!" "Oh, what's wrong? You are powerless within our grasp! This is your end!" (Level 1 Grab Hyper Combo)
- "We will end everything! Inferior creature, you dare defy your God?" (Level 3 Hyper Combo)
- "Insolent fools... Your failure is inevitable..."