I understand that the mentor will be in charge of two heroes here, the map is small for 7 players, and there's nowhere to level up. :)
Some not-so-weak demon appeared as early as the second week of the game https://c2n.me/48fftaj (stats from the tavern are 24-24-40-30). Even though my Frieda is already level 14, and Zephyr is level 11, if he attacks, it's game over.