To instantly destroy a world was a trivial thing for a being of his power. With a simple wave of his hand, he could unleash a single attack without enough force to split the whole planet asunder, leaving nothing but debris and fire in the cold void of space. The mortals of this world and every world he'd visited prior and every world he will visit after certainly deserve such a fate.
The world itself didn't.
Indeed, his current hunting ground, a planet called Earth from the Northern Quadrant, was already a wounded thing. It's sentient species, humanity, ensured that when they performed experiments on their own kind, creating almost unstoppable engines of destruction that annihilated everything in their path for decades. If it wasn't for the meddlesome Saiyan attacking him at every turn, they would most certainly be his main adversaries at this moment.
Such was the case with every sentient mortal species he'd encountered thus far. All of them were given the gift of knowledge, that creative spark enabling them to rise from the primordial muck and attain a true understanding of themselves and their surroundings. A blessing which, when used responsibly, would elevate these selected species to a higher level.
Instead, they simply used it to find new ways to destroy one another in an endless cycle of self-destruction. The city he walked through, or rather the ruins of one, stood as a fine example of this. The buildings created with advanced machinery and through centuries of learning and study stood broken, if they stood at all. Whatever paint was used to give them a more appealing look vanished long ago, leaving nothing but massive chunks of grey and black rock as the city's sole remnants.
Vehicles of every sort littered the empty street ahead of him, more examples of how humanity was no different from every other horrible child of the Gods. If they weren't, the pathetic state of what was once amongst their greatest places of living wouldn't be in this state.
But even amongst the wreckage, he spotted things that validated his method of controlled cleansing instead of pure annihilation. With ilk of mankind gone from this place, nature was reclaiming what belonged to it. Through the cracks of concrete and steel, flowers and other greenery bloomed, creating patches of color and life in the drab dreariness of the overall surroundings. From the corner of his eye, he noticed packs of animals hunting together, something resembling a family unit if the two larger ones and the several smaller children following them were any indication. The four-legged hounds paid no attention to him as they pursued another, much smaller animal through the city.
He bore no ill will to these lesser creatures, they were lead by animal instincts. Simple creatures sometimes capable of more complex thought and emotion but overall simple still. They didn't truly possess the gift of sentience and thus couldn't be judged as harshly as their dominant counterparts, humans. He could no more blame them for their actions than an exploding volcano or a tsunami, they simply did what they did.
His brief examination of the pack was quickly cut short when the ground beneath one of the pups exploded into a million pieces, sending fire, rock and ash blasting into the air. Such attacks had no effect on him, if the Saiyan couldn't hurt him such conventional traps and weaponry certainly wouldn't. With a flick of his hand, he blasted the wind away and narrowed his eyes at the remnants of the pack.
The older ones lived still, horribly mutilated as they were from the mine. Their children were not so lucky, their tiny bodies didn't survive the blast, all that was left of them were strands of bloody flesh. Hearing the survivors whines of misery prompted him to end their suffering with a quick energy wave, vaporizing them and their children to a place where mankind couldn't hurt them anymore.
Bullets were the next attack to come, but not from many directions as they usually did. No, this was a lone gunman firing down on him from one of the few buildings still left standing. He ignored the metal projectiles, letting them harmlessly smash against his skin and clothes as he took off into the air towards the shooter. A black stream of energy surrounded him and left a plane like trail in the sky as he quickly closed the distance between himself and his would-be assassin.
To his surprise, he found an older man wielding the gun trained at him this time around. Usually, the younger ones were responsible for setting up tracks or attacking him. Usually sporting a Capsule Corp jacket of some description as a rallying symbol of sorts, no doubt from a desire to mimic their so-called Saiyan savior. This old man with his balding head, grey mustache, and haunted expression was no different. Perhaps a bit more fanatical in his devotion.
For as he ignored the hail of bullets fired at him, he noticed several pictures placed near his firing position, some of him with his mortal family while others of Trunks and him at some kind of Earthling celebration. No doubt one made in honor of Trunks killing the mechanical monstrosities spawned by one of Earth's "geniuses".
With a swift motion of his hand, he snatched the rifle out of the old human's hand and promptly smashed it against a nearby wall. The elder didn't even know he was being choked until he found himself levitated off the ground with a firm grip placed tightly around his aging neck.
This was the other reason he chose a more personal way of elimination. To see just how low the mortals would sink when their time of reckoning was at hand. In many of their cultures, elders such as these were revered for their tempered minds and experience, yet this one fought with the same fervour and brutality as the younger examples of his kind. Doing whatever it took to perpetuate his own, worthless existence to continue his species cycle of violence. If he was smart, he'd know he deserved what was about to happen to him.
Grabbing the man by the head with his other hand, he used his telepathic abilities to pry into the man's mind. To his surprise, the man wasn't part of Trunks' little resistance force, just a man inspired by it. His obsession with the Saiyan became clear, Trunks saved him from the so-called Androids just when one of them was about to blow his brains out with one of their Earthling firearms.
He thought of Trunks as a hero. A pretty name for just another being who's caused or escalated more senseless conflict elsewhere to resolve his own.
Upon finding the exact locations of the various mines and traps positioned around the place, the man's head was crushed with a deliberately slow movement of the fingers digging into his bones and flesh. His scream echoed throughout the empty building but was quickly silenced when there was nothing left of his skull to scream from.
The display brought a smile to his face.
He was ready to leave when he spotted a small pot containing a flower nearby, one of the few things the old man had left of his deceased wife if his memories rung true. Taking the pot with him, he levitated over the city and with his free hand, telekinetically forced the various explosives made to harm him out of their hiding spots and flung them into the ground. With another loud boom, the devices all smashed into one another and exploded, ensuring the old man's machinations wouldn't cause any more damage from beyond the grave.
He landed at the spot where the first trap killed the family of hounds and blasted a small hole in the ground with a kiai. With care, he took the flower out of the pot and put it in the ground where it could grow free from the interference of mortals. This part of the world was now cleared, the old man was the only one left for a great many miles. But there was more work to do, more humans to eliminate before the Gods mistake was corrected on this world too.
No one was going to stop him from accomplishing this, and with the power of Son Goku's body at his disposal, he doubted anyone really could.
And there you have it! A little closer look into the motivations/psyche of Goku Black! This can honestly take place anywhere in the Super timeline but for fans of my Resurrection F remake, The Vicious Gods Wrath, don't be surprised if this ends up being in-continuity with that too at some point ;)