Han Dong knew roughly what his goals were when he first entered the City of Gods and was assigned his "initial identity" by the System.
Since the World of Fate deliberately suppressed abilities and sealed off items,
it meant to have the participants start from the very bottom of the City of Gods and explore, understand, and fully integrate into this city.
As for the ultimate goal,
it may be to require individuals to achieve a significant status in the City of Gods as slaves,
or it may be to fully explore the hidden secrets and origins of the Black Water in the City of Gods,
or even become the ultimate authority of the City of Gods.
After roughly speculating the purpose of the Fate System,
Han Dong chose to demonstrate his "potential" to the greatest extent in the beast fight arena, revealing his leadership qualities while gaining high visibility by outright killing his targets.
The "Priest" factor was something Han Dong hadn't anticipated.