Heaven Extinction Martial Emperor - Chapter 155 - 154-self-righteous

This is a story about the protagonist getting the system, going crazy in the biochemical apocalypse, producing aircraft and tanks, destroying zombies, saving good people and killing bad people.

- Description from novelbuddy

Chen Yuan transmigrated and became a Mountain Patrol Military Officer.The eight hundred miles of Langdang Mountain is his pasture.Unfortunately, the Great Qian Dynasty is in its final years, with its fate collapsing.Demonic disasters plague the land, bringing devastation to all living beings. The human world becomes a battleground, entering the mortal realm to face calamities.Monstrous beings and malevolent spirits take the stage, disrupting the martial world.Chen Yuan, armed with the Tiger Talisman for Mountain Moving, patrols on behalf of heaven, cutting down mountains and destroying temples.In the eight hundred miles of Langdang Mountain, demons and monsters shall not appear!

Ayaan is a young resident aspiring to be a surgeon, the final stage of a full on graduated plague doctor. However, in her attempt to redeem herself after a sudden discontinuation, she finds herself unravelling mysteries about her institution that are rather gut wrenching. Stick around and watch her persevere in a world full of monsters; creatures and humans alike.

In novels with a stud there is always a Senior Martial Brother like this:

In the early stages of the novel, his innate talent is high, his cultivation is good, his appearance is handsome, and he has an intelligent, cute younger Martial Sister as a fiancée.

In the middle stages of the novel, he is caught unprepared and defeated by a young disciple (the protagonist) in the sect who’s hardly remarkable at all. From then on, he falls from his godly altar and loses his brilliance. Even his young Martial Sister leaves him for someone else.

In the late stages of the novel, he continues to turn dark, going down the Demonic Path and becoming the major villainous boss. However, the protagonist still ruthlessly defeats him and his soul is eternally sealed.

Once Qin Mo opened his eyes, he discovered that he had become this Senior Martial Brother.

- Description from Novelupdates