Criteria

There was a reason that Rui put those two government officials who had contacted him at the top of the list. High-ranking government officials were the most important people in the Kandrian Throne War.

Found Emperor Ra had made it so that the new Emperor could not be officially crowned without their presence and official acknowledgment of the new Emperor. According to Kandrian law, the Coronation Ceremony required at least seventy-five percent of high-ranking government officials to officiate the ceremony for it to be considered official. 

Anything less than seventy-five percent, and the ceremony was invalid.

This essentially meant that during times of throne wars, these government officials collectively had the power of kingmaker. Whichever prince or princess could compel seventy-five percent of the high-ranking officials at the time could become Emperor or Empress as soon as the throne was empty.