From the start, Lin Yu awakens an F-rank card, earning his family’s contempt and becoming a live-in son-in-law. He’s forced to marry Qin Ruoxue, the empire’s S-rank icy female killer, and becomes the laughingstock of the entire city. Don’t panic: the [God-Tier Card Editor] activates! Get ready for a jaw-dropping start!
[Healing Potion (F), upgrade → Sacred Spring of Life (SSS)!] It can bring the dead back to life and restore flesh to bone!
[Goblin Fang (White), enchant → Ancestral Dragon Reverse Scale (Seven-Colored)!] Gods and demons will clamor to possess it!
[Blank Card + Mysterious Blueprint = ???] Speak, and reality obeys. Create the rules!
On their wedding night, his killer wife gives him a cold look. “This is a marriage between our families. We each get what we need, and stay out of each other’s way.” Lin Yu acts meek and obedient. “You’re absolutely right, my dear!” Then he turns around and quietly edits a divine card. Upgrading them is as easy as drinking water!
During the academy’s field training, “accidents” keep happening, and his F-rank cards unleash world-ending effects. Qin Ruoxue narrows her beautiful eyes. “There’s something off about my husband!”
Then a beast horde threatens to destroy the city. The S-rank killer is bleeding in the sky, and the empire is on the verge of collapse! Lin Yu stops hiding. With a wave of his hand, billions of SSS-rank [Thunderclap Imperial Dragon] cards sweep across the battlefield! “Don’t be scared, honey. Your husband can actually create divine cards whenever he wants!”
Qin Ruoxue’s delicate body trembles, her beautiful eyes wide. “I thought you were supposed to be a good-for-nothing live-in son-in-law. You call this F-rank?” The empire’s head of state cries, “This young man… is terrifying! Quick, gather every resource the empire has and ask him to become our guardian deity!” The heir to an ancient card civilization? Enemies invading from another dimension? Lin Yu wraps one arm around his wife and holds the divine card editor in the other. “Don’t panic. Let me edit a [World Reboot] card first!”
It's a little boring at the beginning, but it quickly becomes interesting. Keeping it with a single heroine would make it a good book.