Systemless Villain - Chapter 2: Long Tian’s divergence

A story of time-travel. Sly and cunning, she unexpectedly became a sickly noble lady whose fiancé is merciless and demotes her to a lowly concubine. She sneers and bravely breaks off the engagement. To hell with scumbags, marry heirs to lords, blind the courts with her brilliance.

Violet skies, a world undergoing massive changes, a deficient moon, interlinking voids…
When the world experienced a cataclysmic event,the majority of living things ceased to exist. Although humanity survived by hiding in the last safe zones, humans had to face mutated dire beasts and colossal source beasts that could break through the space barrier and enter the earth at any second.
Luo Yunyang, a young man who grew up in those calamitous times, obtained an attribute regulator and set out to walk the path of supremacy!

- Description from novelupdates

“THE NEW GATE”, an online game that trapped its players and turned into a death game, was now releasing the thousands of players that had been dragged into it, thanks to the efforts of Shin, one of the most powerful players. But after having defeated the last boss and freed everyone, he was swallowed up by a strange light and found himself inside the game world 500 years in the future and unable to leave.

For the wine to be drunk on her wedding night to actually have been a cup of poison and for the one to poison her to be her husband, who would believe it?