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I completed it on hard difficulty without any problems. First, Tyambo gave his warriors to Irina, and through the whirlpool located to the east of the starting city, he headed towards the northeastern corner of the map to recruit neutral units, but before that, he cleared the waters near the whirlpool. By the end of the week, Tyambo had recruited all the desired units. A tip: recruit the Snow Maidens last, otherwise they might start fighting each other. Meanwhile, Irina, using the Phoenix Summon spell, captured the resource mines – first wood, then stone, gold, and crystals. Then, she visited the stables and headed north to capture the Zschwick Castle. With the help of Phoenixes and Restoration, she defeated the Inferno hero and captured the castle. Before the end of the first week, she managed to capture all the resource mines near the two castles. At the beginning of the second week, Irina visited the stables again, went to the Gustav's Turn Castle, received the lighthouse quest, went to the lighthouse, where she met Tyambo, took troops from him, and cleared the lighthouse. By the end of the second week, she already had 3 castles. The rest was just a matter of course. Over the next 3 weeks, she developed the castles, cleared the lands around these castles, and repelled rare attempts by enemy heroes to penetrate her territory. After that, she easily captured the Rauchburg Castle, and since the "We Come in Peace" quest was somehow failed, she captured all the Wolf castles as well. This, along with clearing the territory, took another 3-4 weeks. Then, she attacked the Nebirias Castle, captured it, and went to the Dungeon. By that time, she had almost 200 Holy Kirins, so she didn't experience any difficulties with the Super-Matriarch, nor later with Gerhard. That's all.