Because I've Been Reincarnated as the Piggy Duke, This Time I Will Say I Like You - Chapter 56 - The Collapse of The Barrier

Way, way, and very way before I was even born, my world was invaded. Actually, not just my world, my entire damn universe was overrun by another, led by a single race that called themselves the Eternals.And they were prepared. Very prepared. Every life we lost in the war against them was used by them. They didn’t just kill people, they captured their souls, forged them into Phantoms, and used the souls to twist beasts into Abominations. Our dead became their army.Three hundred years later, I was born. A guy with way too much energy. Sitting still? Impossible. Taking it slow? Not happening. I was always moving, always ready to burst into action. Then I awakened, and got a talent too.My Talent's Name Was Generator.Because of it I never ran out of energy. Ever. My muscles? Supercharged. My healing? Faster. My stamina? Please, I had no idea what being tired even felt like.So if the universe wanted to throw an endless war at me?Fine. I’d throw everything I had right back.I wasn’t born a hero. Never wanted to be one. But this war? It wasn’t just my universe’s fight anymore. It was mine. The Eternals made sure of that when they took my parents' souls.

With the Legendary Mechanic System, I transmigrated to Marvel Universe to be Dr. Zola’s assistant.

With Mechanical Force Analysis, I can learn every black technology.

Winter Soldier’s arm? I built a better one for you.

Iron Man’s armor? I already made it a decade earlier.

Doc Ock’s tentacles? I am the one who provided core technology.

Hulk’s mutation? Sorry, I was there and got hit by the radiation too.

As for a certain purple potato, can he collect all Infinity Stones?

……

However, I only had one simple ultimate dream. That is to go home…

- Description from Novelupdates

In this world, orphans or just anyone without any hope for this world can apply to become a “walking target”. Their sole purpose is to be a practicing dummy for the students of the sect who train to become “Demon Hunters”. These students need “walking targets” to test their training on living, walking beings of flesh and blood.
In exchange, they will be provided with food & shelter.
Their existence value is lower than a slave, but if they manage to survive a few years they can receive a life long pension.

Xiao Han is such a “walking target”. One time he witnessed a powerful Demon Hunter disposing a demon. When the demon died, a fragment of the demon that managed to escape entered Xiao Han’s heart. No one saw that, and even Xiao Han himself only felt some discomfort for an instant.

But that thing in his heart soon gave Xiao Han visions, and the first one is of a cultivation method which allows Xiao Han to absorb damage to enhance his body. A perfect cultivation method for a “walking target”.

- Description from Novelupdates