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Hooray!!! I made it!!!! I can't really give any specific recommendations though ))))) (I was quite tipsy), but I'll tell you something.
1. I developed my hero as a ranged attacker and for logistics.
2. I didn't spend much time in the Dungeon; I sailed to the first city on a ship.
3. (Maybe it's not important) The first time I arrived at their first city, there were too many enemies, and a hero with 4 Imps was standing near the gate. I attacked him. Then I went to capture the mine. On the next turn, the computer bought another level 1 hero with a corresponding army and attacked me again! This happened several times... I didn't count. Then, a hero with a large army emerged from the castle and wreaked havoc on me (I had to remember my tactics). I think I managed to chip away at their gold reserves a bit. Anyway, without waiting for a powerful hero, I jumped on my ship and sailed back to my city for reinforcements. While I was sailing back and forth, their powerful hero emerged from the castle and started capturing the mines I had managed to seize. I also fought some neutral creatures. When I arrived again, he didn't have time to enter the city and was defeated, albeit with significant losses. The city was taken!!! The Dragon joined me!
4. By this time, I had spotted two obelisks, which I visited after gathering additional troops. We sailed further. There's basically only one sea route to follow. We arrived at the next island, where there was another obelisk, several mines, and, if I'm not mistaken, an entrance to the Dungeon. We checked out the obelisk and took the mines. I didn't pay much attention to any "gifts" if they were heavily guarded. I only attacked those where I was 100% sure of victory without losing any troops. I jumped back on the ship and sailed to collect the dragons that were gathering along the way to my original castle (there were 3 of them on this island, I think). While I was sailing and collecting them, another red hero appeared and dove into the Dungeon. I barely made it back to the city in time to meet him there. (I replayed that battle 3 times. I only calmed down when I had 3 dragons left out of 6).
5. After that, everything went smoothly. I entered the Dungeon (there's another obelisk there) and continued to capture red heroes (they made a few more attempts to reach my cities). In the Inferno city, I also bought a hero; he was intercepting my ships.
That's pretty much it.
P.S. I collected a total of 27 dragons on the map. 7 were lost in battles