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I enjoyed the mission, although I was initially puzzled. There are too many blue (and later red) units running around the map. The solution came to me naturally. I gathered taverns, leveled up secondary heroes, and gave them a portion of the army (sometimes a ballista + goblins + a couple of dozen centaurs was enough). I gave one a decent army, equivalent to two weeks' worth of reinforcements, and left another in the castle to simply accumulate leadership (with a perk for increased reinforcements).
I restarted once because of a catapult: I needed to destroy 6 phoenixes guarding the shipyard within two weeks, otherwise, they would use artillery to decimate our reinforcements across the river. At the same time, it's desirable to collect some loot a little further south, because on the 2nd or 3rd week, a red player will arrive (with a fairly strong army). He also steals boats by summoning them, which we can try to use to our advantage and trap him somewhere.
Gradually, we capture the castles to the north, on the left and right, and gain resources from them, which makes things more interesting. Now there are enough resources and money to build a castle and buy a full army. We take the main chests for money, and secondary heroes can take them for experience, but there's no point in leveling them above level 10 (it's enough to just give them some logistics, defense, attack, or leadership).
I didn't usually play with the ballista; it's better to use a tent with wyverns. I was pleased with the additional quest with the elementals and the underground dead end with the dwarves, where I jumped through a whirlpool closer to the end. In the end, I locked the blue player in a castle and defeated the red player on the left with catapults. After clearing the entire map and collecting stat bonuses, I went to finish the game, but the castle's defense didn't increase, so it was a bit slow. I thought for a long time between choosing: full artifacts from the lion set or a necklace for a unique skill, mastery of something. A necklace is still better when you have a large army, right?!