Citadel for All: The Only Unit Angel at the Start of the Game - Chapter 597

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

Throughout heaven and earth, I alone am powerful

Shen Weiyi has a younger, boy-next-door boyfriend whose allure lies in his height, long legs, and strong torso. With a wild mind and a talent for flirting, the eighteen-year-old Jiang is impulsive, fun-loving, and fickle, exhibiting both innocent and wolf-like traits at the touch of a button. Beloved by countless girls, he always thought Shen Weiyi, who would do anything at his mere call of 'sister', would forever indulge him, only to find she suddenly doesn't want him anymore.Breakups are breakups; whoever regrets it is a dog.Shen Weiyi, once red-eared and compliant to his every whim, now won't look back, leaving an eighteen-year-old Jiang's genuine liking turning into a resolute declaration of disinterest. 'Jiang,' she says, 'I date for happiness, not for extra headache.'Later, a desperate Jiang tries everything for her, getting injured in the process and lowering himself to the dust, only to see her blooming in another man's arms, which drives him to a jealous rage.Sheng Ting, the genius of the Z University, untouchable and seen by everyone as the embodiment of purity and restraint, had decided the names of their unborn children upon his first glimpse of Shen Weiyi.[Childhood friend VS Sudden love, not seeking the adoration of the whole world but asking to be your one and only exception in life.]

In a modern world where cultivators need a place to cultivate or vent their boredom, there are private businesses that set up instance dungeons with the aid of technology and cultivation magic to enable cultivators to train and commoners to experience the life of cultivation. They are called dungeon suppliers.
Xie Jin's one and only dream was to be a dungeon supplier and when his only relative passed away, the relative's inheritance gave him a plot of land and surprisingly, a 'System' Module which the relative had previously used.
With the help of the system, Xie Jin decided to pursue his dream of becoming the number one dungeon supplier.