I had little money and played the entire game with 5 heroes, taking a Golem and a couple of Imps as support. On day 115, I captured a village, and on day 117, I encountered the opponent. He had 30 blue creatures and 4 demons, while I had 21 Golems, 2 Ifrits, and a Ballista, with higher combat stats. I killed 20 of the blue creatures, and he offered a truce. The next day, he surrendered. Gundula "marked" his main hero, and the opponent decided not to continue.
Thank you for the game!