It's been a while since I last picked that one up, so I'm working from memory here. Chapter 17 was right in the thick of the protagonist's early power consolidation, I believe. He'd just gotten past the initial system tutorial phase and was starting to face real external pressure from a local martial family in the city.
If I recall, the core of the chapter was a confrontation with a young master from a rival clan who was trying to seize a herb field or a low-level spirit stone mine the MC had just secured. The system issued a timed mission to defend the territory, offering a reward that would unlock a new cultivation technique. The fight itself wasn't overly long, but it was the first time he used a system-bought combat skill in a life-or-death situation, which made his internal monologue pretty frantic.
He won, obviously, but not without taking a decent injury that set up the need for a healing arc in the next few chapters. The writing focused a lot on the visceral shock of real combat versus training, and the system's cold, points-based evaluation of his performance afterwards felt appropriately jarring.