I Said Make My Abilities Average! - Chapter 390 - Defense Battle 4

Kai of the Sorcerer’s Tower is one of the last mages left, barely surviving in a world ruled by creatures of the dark — where the era of mages ended, and most of the lands got contaminated with dead mana. To save his world and fulfil his master’s last wish, he put himself through a forbidden ritual, risking his soul being ripped into pieces to make his way into the past. In an era with abundant mana — an era yet to enter the Golden Era of Magic. Things go wrong, of course, as they always do, and he finds himself thousands of years before the world fell to mana contamination — in the body of a young lord, Arzan. All is not well, though, as the young lord was murdered by someone right at the cusp of a beast wave threatening the territory, while larger threats loom on the horizon. There was a lot to do for Kai to regain his former strength in this time of primitive technology, but then again, he might just be able to change that.

One day, Luo Jian woke up from his sleep and found himself in a locked chamber where the door and window were all sealed. A note with a few lines written on it was tacked to the wall: “Escape from this room within an hour, otherwise, you will die.”

There is a sequel called Reincarnation Night (轮回之夜) that takes place in the same universe but has different main characters

- Description from Novelupdates

An avid Xianxia reader suddenly has his dream come true—he wakes up in a world of cultivation. The only problem? Maybe it wasn’t really his dream after all.Now, faced with the daunting reality of countless cultivation realms to climb, countless worlds to ascend through, and countless arrogant young masters to deal with, despair begins to settle in.Fortunately, a glimmer of hope appears amidst the chaos: a mysterious system that could change everything.Armed with elders, ancestors, and a sect leader—who are all actually his own avatars—he no longer feels completely overwhelmed.“At least I don’t have to do it all alone… well, technically, I do. They’re just avatars, after all.”