Because he killed the important demon present in the [Ancestral Mansion].
A path leading out of the mansion opened on its own.
Han Dong didn't get greedy and continue further into the mansion. Dealing with Marysia had nearly exhausted his stamina, even the Count was panting for breath…
Plus, the spoils were considerable.
In addition to acquiring the crystal stone, Han Dong officially verified the effectiveness of the Abyssal Bloodhound Arm in real combat.
In the last stretch of the fight, with the special properties of the Chaos District and the awakening of his left arm, he dove his consciousness deep into a death temple in Ancient Egypt. There he wrung out energy at the cost of exhaustion, performing dark magic that transcended his current level.
This also indirectly proved how potent the left arm's potential was, fully deserving of Han Dong's investment in it.
…
Under the dual pressures of the demon and Han Dong.