Primordial Ancient Serpent - Chapter 1 - : The Primordial Ancient Snake

A master of Chakra Cultivation sacrifices everything - only to be reborn with a second chance.After giving his life to save his world, Alaric awakens in the body of a child. In this new realm where power is measured in tiers, bloodlines, and the strength of one's oaths, Chakra Cultivation is an unknown path.As Alaric purifies his chakras, each one unlocking profound abilities across body, mind, and soul, he gains an edge no native warrior can match. But his true test awaits in the Tower of Trials—a rite of passage for the world's young elites, offering immense rewards to those who can climb its treacherous heights. No one has ever reached its highest levels.If mastering his reborn powers wasn't hard enough, his journey will forge a bond with an entity of unimaginable strength - and lead him to lands where no mortal has dared to tread.

The world that nurtured the civilization which reached the pinnacle of magic was on the verge of destruction.
The last survivor transmigrated to the past, when the magic civilization started growing, as countless mages were still fumbling their ways through the thorny paths of magic knowledge.
He, who came from the end of the magic era, aim to reach the pinnacle of magic.

- Description from Novelupdates

'Death' It was meant to be the end, but it brought a new start.After a destructive nether storm consumes his world, Jack finds himself face-to-face with a powerful being who tasks him with a mission he can’t refuse.Reincarnated as Asriel—the most tragic, doomed character from a novel he once read—Jack’s frustration grows: “Damn it, why this fool?”Now, he must navigate Asriel's cursed life, facing relentless supernatural beings that threats him with a single hope:[Necromancy System Activated!][Ascend as the Ruler of the Undead!]But can Jack rise above Asriel's fate, or will he, too, fall prey to the shadows lurking in his new world?

This crossing is so strange, death crossing, game crossing, etc. are probably barely acceptable, but why can you cross even if the fish tank is broken?

and actually passed through the magic tree in “OVERLORD” that is said to be able to destroy the world?

No! It is sad enough to regenerate into a plant. The protagonist, Ainz Ur Gong, the undead king, has also accepted the adventurer’s guild mission and wants to kill me!

I want to change my destiny! Live! I want to-surrender!

Ainz: Since he has accepted the job commission from the Adventurer’s Guild, deliberate failure is detrimental to the prestige of Ainz Ul Christine (the “surrender” button has been deducted)

actually died as soon as he crossed, but there is still a chance to return~ from the beginning of the magic tree to this world.

I must change my destiny this time! Live!

- Description from novelbuddy