I recommend "Instant Upgrade". The protagonist of this book can level up instantly by killing enemies. One slash can level up one level, nine slashes can level up two levels, and even more than a hundred slashes can level up to level nine! Moreover, this book had various divine artifacts, cultivation techniques, and martial techniques that could be upgraded to become the most powerful existence. If you want to read a fantasy novel that upgrades quickly, this is definitely not to be missed! I hope you like this fairy's recommendation. Muah ~😗