A hidden Imperia encounter can be fought by running around through Imperia at night. On the road leading down to the beach between Caltha and Cro Beska, you will encounter Mutuus walking alone. Get in his way and he will tell you to get out of his way. Get in his way again and he will tell you that this is your final warning. Get in his way a third time and he will tell you that he is going to teach you a lesson. . Before you get in Mutuus' way for the third time, make sure to save the game; any death during this encounter is permanent. You will be taken to a wilderness encounter screen where you will have to fight five Imperials, ranging from Centurions to Murmillos, Peltasts, Samnites and Secutors (any mixture thereof, the selection is random and different every time). Choose your fighters based on countering Mutuus' crew and you will succeed. Your reward is a large amount of experience points.