Retaining the arrogance and self-entitlement of Goku Black and Future Zamasu, this fusion believes himself to be the embodiment of justice. Reveling in his power, Zamasu openly declared himself the supreme god upon his emergence, repeatedly and consistently vocalizing his divine brilliance and absolute authority. His ego is displayed by how he refuses to even defend himself against Goku and Vegeta (which continues to some extent until Goku blasts off half of his face during a beam struggle), his tendency to hover high over the battlefield to "look down" on everyone both figuratively and literally, and his use of "divine" terms (such as "holy", "judgement", and "absolution") to name his special techniques.

However, beneath his calm exterior, Fused Zamasu is just as unstable as his components, if not more so; according to Gowasu, this is the result of Zamasu's obsession and hatred with the contradiction between gods and mortals. He immediately flies into an overwhelming fury when Trunks and Vegeta briefly overpower him in their beam struggle, despite suffering no damage from the deflected attack, and his rage only grows when Goku manages to actually harm him with God Kamehameha and Kaio-ken. After having the right half of his body harmed, and being mutated by the Light of Justice, Fused Zamasu becomes more unhinged and maniacal, prone of furious outbursts. This is due to the fact that his physical body is deteriorating and the conflicting of the souls of the immortal Future Zamasu and mortal Goku Black that make up his form. By the time he engages Vegito and Future Trunks, Fused Zamasu is reduced to insane and enraged screaming and furious declarations of godhood, ironically becoming just as destructive and violent as the mortals he wishes to exterminate. In the manga, however, he retains his arrogance, openly gloating and overjoyed at his power. Although he does get angry at Gowasu for neglecting to mention that a permanent fusion can only be achieved by those officially designated as Supreme Kais. Similarly, upon Vegito defusing, he also calls Goku and Vegeta out for using the sacred treasure of the Gods.

Interestingly, Fused Zamasu is well aware of his own hypocrisy in taking on mortal elements by using Goku Black as a fusee. He views this as a necessary sacrifice to truly create his new world; by using Goku's body as part of his being, he intends to never forget the "sins" of mortals and the "failures" of the gods. He also states that his actions are for the greater good of the universe, even crying at its thought, and metaphorically described his tears as purifying the world. Similarly, he also stated when demanding the Light of Divine Justice strike him that a weak god who cannot destroy evil is "worthless", implying that he can only find value in his existence by being powerful and more importantly, being capable of vanquishing what he considers evil. In the manga, however, once Zamasu's insanity gets the better of him, he drops all pretenses of justice and declares that all the gods are unnecessary and that he will kill every life form in all realities that is not a version of himself.

In the anime, by calling upon the Light of Divine Justice, Fused Zamasu becomes larger and more muscular. In this form, he is named Grotesque Zamasu, Fused Zamasu (Right Arm Enlargement) or Fused Zamasu (Half-Corrupted).

His aura changes from colorful white to that of Black's as Super Saiyan Rosé. Despite the great increase in power, the flawed nature of Fused Zamasu's body comes with a side-effect of his body mutating, resulting in half of his body becoming an oversized and purple gooey substance. Grotesque Zamasu also has his right eye to gain a purple iris and yellow sclera.

As a result of his great anger at losing to Vegito, combined with the forced mutation from his Light of Justice, Fused Zamasu bulks himself up and grows to become huge. He is able to survive Super Saiyan Blue Vegito's Final Kamehameha.

It is stated that due to being a sync up of two versions of Zamasu, Fused Zamasu's fighting skill is far greater than before. He even shows off speed greater than any character in Dragon Ball prior to this to take down Super Saiyan God Goku and Vegeta. Later, Super Saiyan Blue Goku manages to hold his own against Fused Zamasu in one on one (though Fused Zamasu has a large advantage) and even blasts a hole through Fused Zamasu with a God Kamehameha, however, the fusion simply regenerated and takes down Goku by hitting him with many blocks of Katchin.

Fused Zamasu had his entire side blown off by base Vegito (though it was a surprise attack) and was shown to have a great disadvantage against Vegito Blue, who was noted by Shin to have power potentially surpassing Beerus, with Fused Zamasu being unable to track Vegito Blue's movements at one point, allowing the fused Saiyan to cut off his hands without him noticing.

After Vegito defuses, Fused Zamasu faces off against Goku, who reveals his mastery of Super Saiyan Blue that he had been hiding. Fused Zamasu is a match for Goku in this state, which possesses the true full power of Super Saiyan Blue at all times and manages to hold the edge over Goku thanks to his immortality. Vegeta states that using completed Super Saiyan Blue, Goku can fight evenly with Fused Zamasu. When enraged at Goku's continued resistance, Fused Zamasu claims he will destroy the entire galaxy once the fight is over.

As the Potara Fusion of Goku Black and Future Zamasu was performed while Black was still in his Super Saiyan Rosé state, Fused Zamasu is constantly and permanently in the Super Saiyan Rosé form. Because of this, the resulting fusion cannot enter a normal form nor power down. While this would normally cause a significant strain on the fusion's body and shorten his lifespan, the immortality from Future Zamasu, to an extent, eliminates this problem despite the "unstable" fusion affected by Goku Black (as his body isn't immortal). In the manga, he also retains his hour limitation for staying fused due to not being a true Supreme Kai. However, he was able to stay fused for the full hour, despite Super Saiyan Rosé being a Super Saiyan God Super Saiyan form; with its equivalent Super Saiyan Blue causing Vegito to defuse faster than originally estimated. Even when the fusion ran out, the fact that the two Zamasus were the same person resulted in them rejecting this, resulting in a new combined state.

Fused Zamasu's physical appearance in the Super Saiyan Rosé form is that of a standard Super Saiyan with white hair and grey eyes. The white hair and grey eyes were presumably inherited from Future Zamasu, however, Fused Zamasu's eye color could possibly be inherited from the Super Saiyan Rosé form as well. Furthermore, Fused Zamasu possesses a bright, colorful white aura while in the Super Saiyan Rosé form in the anime, while he lacks an aura in the manga. Fused Zamasu remains in the Super Saiyan Rosé form throughout all of his appearances in all Dragon Ball media, except as Infinite Zamasu in the anime.

As a fusion of Future Zamasu and Goku Black, Fused Zamasu possesses all the techniques and abilities of his fusion components and more: Flight - Fused Zamasu is capable of flight using his ki. Continuous Energy Bullet - Fused Zamasu can unleash this attack from a single hand. Appears in Xenoverse 2 it appears as Fused Zamasu's unique Strong Attack. Immortality – The ability to remain unchanged by the passage of time, unable to die, and simply live forever. This power was obtained from Future Zamasu, who wished for it through the Super Dragon Balls. In the anime, as a result of Goku Black's presence within his being, Fused Zamasu is not completely immortal; only ageless and possessed an enhanced durability with high tolerance for pain and damage. While his semi-immortal body can be destroyed, Fused Zamasu can still live on in a bodiless state that has assimilated with the very universe itself, unless every single trace of him is gone. In the manga Fused Zamasu's immortality is fully intact, and likewise allows him to maintain an edge over Goku's Perfected Super Saiyan Blue form. In Dragon Ball Heroes it is implied by Fused Zamasu that his immortality allowed him to survive Future Zeno's attempt to erase him. Regeneration – Fused Zamasu heals any wound he may incur. However, depending on the version, the extent of his regeneration abilities vary: In the manga, Fused Zamasu heals up from a hole in the chest immediately with absolutely no problems, while in the anime, due to his fusee, Goku Black, still being mortal, it takes him much longer to heal, resulting in his misshaped state. However, in the manga, due to Fused Zamasu's regeneration being fully intact, his body prevented itself from defusing when his time was up, resulting in an unstable state where somehow even his own pieces of his body could actually regrow into Fused Zamasu's with all of his power intact. Saiyan Power - Obtained from Goku Black, Fusion Zamasu is able to become considerably stronger after recovering from damage he sustains from his enemies. Alteration-type ki manipulation technique - A special ability used to extend and form ki into various shapes as well as change its properties. Products used as part of his standard combos and Super Attacks in Dragon Ball Xenoverse 2. Barrier of Light - In the anime, Fused Zamasu creates a white halo of light around his body, which acts like a barrier. Wall of Light – Fused Zamasu emits a powerful purple bird-like structure of enormous energy which eliminates all that it touches. Absolute Lightning - Fused Zamasu fires a purple-colored lightning blast from his ring of light, or the body of his Wall of Light. Blades of Judgement - From his halo, Fused Zamasu fires a barrage of red energy blades that can strike the opponent. If the blades make contact with the earth, they will burst in a destructive explosion. Hammer of Judgement - A modified version of Fused Zamasu's Blades of Judgement attack, in which he fires a hail of powerful red energy blasts from the sky to strike his opponents. Zamasu used this attack as a Core Area Warrior. Violent Fierce God Slicer - Fused Zamasu can create a purple blade of ki which emanates from his hand. Azure Dragon Sword Model Energy Blade - Goku Black's improved version of the Violent Fierce God Slicer also used by Fused Zamasu. Holy Light Grenade - A more powerful version of the Black Power Ball, being larger and orange or purple in appearance. Human Extinction Attack - An energy barrage version of the Holy Light Grenade. In the manga, Fused Zamasu used this technique in an attempt to kill Goku, Vegeta, Future Trunks, Future Mai, Shin, and Gowasu. Divine Wrath - A variation of Fused Zamasu's Holy Light Grenade where radiates his halo and from his hand, he releases a purple energy blast, that obliterates his opponents. One of his unique Special Moves in Dragon Ball Fusions. Holy Wrath - Fused Zamasu creates a sun-like energy sphere that combines Black Power Ball with God Splitter and tosses it at his opponent, expanding it to a large size. In Dragon Ball Super it is Fused Zamasu's ultimate attack, though in Xenoverse 2 it is a Super Skill and is depicted as a weaker version of Divine Wrath: Purification. Divine Wrath: Purification - An upgraded version of Holy Wrath already in a large energy sphere. Appears in Xenoverse 2. Holy Imperial Wrath - Fused Zamasu's super attack as a Core Area Warrior. Energy Blade - A blade made of ki. One of Fused Zamasu's Special Moves in Dragon Ball Fusions. Super Energy Blade - A stronger version of Energy Blade and one of Fused Zamasu's learnable Special Moves in Dragon Ball Fusions. Spirit Blade - A variation of the Energy Blade which differs in both size and color. Can be learned as a Special Move by Fused Zamasu after reaching Lv. 36 in Dragon Ball Fusions. Super Spirit Blade - A stronger version of Spirit Blade which can be learned by Fused Zamasu as a Special Move in Dragon Ball Fusions. Divine Hammer - An attack/fighting style used by Grotesque Fused Zamasu where he punches his foe and swings his arm to create wind slashes as well as hurricanes. Sacred Wave - With his arm severely mutated by his Light of Divine Justice, Fused Zamasu creates shockwaves from his attacks. Spiral of Condemnation - A variant of the Divine Hammer hurricane attack except Fused Zamasu uses ki to amplify his whirlwinds he creates when using Divine Hammer. Light of Divine Justice - A powerful, self-harmed thunderstorm-like energy wave attack that powers Fused Zamasu up. This is what caused him to further mutate his arm and gain his full Mutation. This technique also appears in Xenoverse 2 as an eye blast Super Attack exclusive to Half-Corrupted Zamasu. Flames of Retribution - Zamasu shines red and bursts out ki from all over his body, starting from his right eye. Magic Materialization - In the manga, Fused Zamasu is able to use magic materialization in order to create blocks of Katchin. He is also able to restore his damaged clothing. Supernatural Abilities - Fused Zamasu summons forth a block (or multiple blocks) of Katchin and tosses it at his opponent. Telekinesis - In the manga, Fused Zamasu uses telekinesis to manipulate blocks of Katchin to throw at his foes. Choke - In the manga, Fused Zamasu uses telekinesis to choke both Goku and Vegeta Portal Opening - In the manga Fused Zamasu possess the ability to open dark portals. Illusion Smash - Through his ability to open portals, Fused Zamasu is able to open a portal near himself and near his opponent so he can punch them from a distance. Kiai - A technique where the user affects the air currents around him with ki to produce powerful shockwaves in order to strike the opponent. Used by Fused Zamasu as part of his combos in Xenoverse 2. Invisible Eye Blast - A technique involving the user to shoot a kiai out from their eyes. Used by Fused Zamasu in the manga. Summoning - In Dragon Ball Fusions, Fused Zamasu has the ability to summon incarnations of himself from different time-spaces, however, if he is defeated, they will disappear, as he is their link to that time-space. Black Kamehameha - Goku Black's Kamehameha technique. One of Fused Zamasu's Special Moves in Dragon Ball Fusions. Magical Thunder - Fires a bolt of magical energy from his finger. One of Fused Zamasu's Special Moves in Dragon Ball Fusions. Psychic Thunder - A stronger version of Magical Thunder that appears as one of Fused Zamasu's learnable Special Moves in Dragon Ball Fusions. Illusion Thunder - A version of Magical Thunder that is even stronger than Psychic Thunder that appears as one of Fused Zamasu's learnable Special Moves in Dragon Ball Fusions. Energy Charge - A ki charging technique used by Fused Zamasu as one of his Special Moves in Dragon Ball Fusions. Divinity Unleashed - A ki charging technique used by Fused Zamasu to combine the two sources of his power into himself which gives him the power to create the Barrier of Light in Dragon Ball Super. Was named in Xenoverse 2 where it appears as one of Fused Zamasu's Super Skills. It can be used as a variant of the Full Power Charge for the Future Warrior. Break Strike - An explosive wave that launches nearby opponents upward. Used by Fused Zamasu in Xenoverse 2 as Fused Zamasu's Evasive Skill. Electric Shock - Fused Zamasu grabs his opponent and uses his ki to electrocute them, causing them debilitating pain. This is his unique grab animation in Xenoverse 2.