For each time you fight, you are able to level up and unlock new story. Leveling up will increase stats and increase luck. Leveling up require 0.1 BNB.
Princess can Vow after leveling up 5 time. Changing their outlook and increase all of their stats.
Princess Vow require 1 BNB, interms of PSRG. After vowwing , the stats of princess will increase by 25%, the Luck of princess will be increased by 40.